CR Questions 11 - 20

Questions 11-12 are based on the following.

To protect certain fledgling industries, the government of country Z banned imports of the types of products those industries were starting to make. As a direct result, the cost of those products to the buyers, several export-dependent industries in Z, went up, sharply limiting the ability of those industries to compete effectively in their export markets.

11. Which of the following can be most properly inferred from the passage about the products whose importation was banned?

(A) Those products had been cheaper to import than they were to make within country Z’s fledgling industries.

(B) Those products were ones that country Z was hoping to export in its turn, once the fledgling industries matured.

(C) Those products used to be imported from just those countries to which country Z’s exports went.

(D) Those products had become more and more expensive to import, which resulted in a foreign trade deficit just before the ban.

(E) Those products used to be imported in very small quantities, but they were essential to country Z’s economy.

12. Which of the following conclusions about country Z’s adversely affected export-dependent industries is best supported by the passage?

(A) Profit margins in those industries were not high enough to absorb the rise in costs mentioned above.

(B) Those industries had to contend with the fact that other countries banned imports from country Z.

(C) Those industries succeeded in expanding the domestic market for their products.

(D) Steps to offset rising materials costs by decreasing labor costs were taken in those industries.

(E) Those industries started to move into export markets that they had previously judged unprofitable.

13. The difficulty with the proposed high-speed train line is that a used plane can be bought for one-third the price of the train line, and the plane, which is just as fast, can fly anywhere. The train would be a fixed linear system, and we live in a world that is spreading out in all directions and in which consumers choose the free-wheel systems (cars, buses, aircraft), which do not have fixed routes. Thus a sufficient market for the train will not exist.

Which of the following, if true, most seriously weakens the argument presented above?

(A) Cars, buses, and planes require the efforts of drivers and pilots to guide them, whereas the train will be guided mechanically.

(B) Cars and buses are not nearly as fast as the high-speed train will be.

(C) Planes are not a free-wheel system because they can fly upon between airports, which are less convenient for consumers than the high speed train’s stations would be.

(D) The high-speed train line cannot use currently underutilized train stations in large cities.

(E) For long trips, most people prefer to fly rather than to take ground level transportation.

14. Correctly measuring the productivity of service workers is complex. Consider, for example, postal workers: they are often said to be more productive if more letters are delivered per postal worker. But is this really true? what if more letters are lost or delayed per worker at the same time that more are delivered?

The objection implied above to the productivity measure described is based on doubts about the truth of which of the following statements?

(A) Postal workers are representative of service workers in general.

(B) The delivery of letters is the primary activity of the postal service.

(C) Productivity should be ascribed to categories of workers, not to individuals.

(D) The quality of services rendered can appropriately be ignored in computing productivity.

(E) The number of letters delivered is relevant to measuring the productivity of postal workers.

15. Male bowerbirds construct elaborately decorated nests, or bowers. Basing their judgment on the fact that different local populations of bowerbirds of the same species build bowers that exhibit different building and decorative styles, researchers have concluded that the bowerbirds’ building styles are a culturally acquired, rather than a genetically transmitted, trait.

Which of the following, if true, would most strengthen the conclusion drawn by the researchers?

(A) There are more common characteristics than there are differences among the bower-building styles of the local bowerbird population that has been studied most extensively

(B) Young male bowerbirds are inept at bower-building and apparently spend years watching their elders before becoming accomplished in the local bower style.

(C) The bowers of one species of bowerbird lack the towers and ornamentation characteristic of the bowers of most other species of bowerbird.

(D) Bowerbirds are found only in New Guinea and Australia, where local populations of the birds apparently seldom have contact with one another.

(E) It is well known that the song dialects of some songbirds are learned rather than transmitted genetically.

16. A greater number of newspapers are sold in Town S than in Town T. Therefore, the citizens of Town S are better informed about major world events than are the citizens of Town T.

Each of the following, if true, weakens the conclusion above EXCEPT:

(A) Town S has a larger population than Town T.

(B) Most citizens of Town T work in Town S and buy their newspapers there.

(C) The average citizen of Town S spends less time reading newspapers than does the average citizen of Town T.

(D) A weekly newspaper restricted to the coverage of local events is published in Town S.

(E) The average newsstand price of newspapers sold in Town S in lower than the average price of newspapers sold in Town T.

17. A drug that is highly effective in treating many types of infection can, at present, be obtained only from the bark of the ibora, a tree that is quite rare in the wild. It takes the bark of 5,000 tree to make one kilogram of the drug. It follows, therefore, that continued production of the drug must inevitably lead to the ibora’s extinction.

Which of the following, if true, most seriously weakens the argument above?

(A) The drug made from ibora bark is dispensed to doctors from a central authority.

(B) The drug made from ibora bark is expensive to produce.

(C) The leaves of the ibora are used in a number of medical products.

(D) The ibora can be propagated from cuttings and grown under cultivation.

(E) The ibora generally grows in largely inaccessible places.

18. High levels of fertilizer and pesticides, needed when farmers try to produce high yield of the same crop year after year, pollute water supplies. Experts therefore urge farmers to diversify their crops and to rotate their plantings yearly. To receive governmental price-support benefits for a crop, farmers must have produced that same crop for the past several years.

The statements above, if true, best support which of the following conclusions?

(A) The rules for governmental support of farm prices work against efforts to reduce water pollution.

(B) The only solution to the problem of water pollution from fertilizers and pesticides is to take farmland out of production.

(C) Farmers can continue to make a profit by rotating diverse crops, thus reducing costs for chemicals, but not by planting the same crop each year.

(D) New farming techniques will be developed to make it possible for farmers to reduce the application of fertilizers and pesticides.

(E) Governmental price supports for farm products are set at levels that are not high enough to allow farmers to get out of debt.

19. Shelby Industries manufactures and sells the same gauges as Jones Industries. Employee wages account for forty percent of the cost of manufacturing gauges at both Shelby Industries and Jones Industries. Shelby Industries is seeking a competitive advantage over Jones Industries. Therefore, to promote this end, Shelby Industries should lower employee wages.

Which of the following, if true, would most weaken the argument above?

(A) Because they make a small number of precision instruments, gauge manufacturers cannot receive volume discounts on raw materials.

(B) Lowering wages would reduce the quality of employee work, and this reduced quality would lead to lowered sales.

(C) Jones Industries has taken away twenty percent of Shelby Industries’ business over the last year.

(D) Shelby Industries pays its employees, on average, ten percent more than does Jones Industries.

(E) Many people who work for manufacturing plants live in areas in which the manufacturing plant they work for is the only industry.

20. . Some communities in Florida are populated almost exclusively by retired people and contain few, if any, families with small children. Yet these communities are home to thriving businesses specializing in the rental of furniture for infants and small children.

Which of the following, if true, best reconciles the seeming discrepancy described above?

(A) The businesses specializing in the rental of children’s furniture buy their furniture from distributors outside of Florida.

(B) The few children who do reside in these communities all know each other and often make overnight visits to one another’s houses.

(C) Many residents of these communities who move frequently prefer renting their furniture to buying it outright.

(D) Many residents of these communities must provide for the needs of visiting grandchildren several weeks a year.

(E) Children’s furniture available for rental is of the same quality as that available for sale in the stores.

Official answers and explanation --

11. In Z, when the government banned imports of certain products the cost of those produces rose, so the products
must have been cheaper to import than they were to make in Z. Therefore choice A is the best answer.
None of the other choices can be inferred. Country Z need have had no plan to export those products later (choice B), nor need the products have come previously from those countries to which country Z exported goods (choice C). The products need not have become more expensive before the ban (choice D), and they could have been imported in relatively large quantities (choice E).

12. When the cost of the products rose, the competitive ability of those export-dependent industries that bought them was sharply limited. This fact strongly supports the claim that those industries did not have sufficiently high profit margins to enable them to absorb the price increase, so choice A is the best answer.
Given the limitation on their competitive ability, it is unlikely that those industries would be able either to expand
their domestic markets (choice C) or to enter into new export markets (choice E). The other choices relate
situations that would be possible but that are not strongly supported: other countries could have continued to
permit imports from Z (choice B), and the industries may have unable to decrease labor costs (choice D).

13. The author argues that planes, since they are a free-wheel system, will be preferred to the high-speed train. Choice C weakens the argument by pointing out that planes are not a free-wheel system and are les convenient than the high-speed train would be. Thus C is the best answer.
The special feature of the high-speed train described in A is not one that clearly affects consumer choice one way or the other way. Since it is planes that would compete effectively with the proposed trains, the fact that cars and buses might not do so is irrelevant. Non-availability of certain station (choice D) and the consumer preferences described in choice E tend to make the proposed train less, not more, attractive and so both choices strengthen the argument.

14. The critique of the proposed purely quantitative measure of productivity raises the issue of quality of service, which implies that quality of service is a potentially relevant consideration. Thus, choice D is the best answer.
The objection assumes that postal workers are a suitable illustrative example of service workers in general; thus,
choice A is inappropriate. By delivery of letters, the argument treats letter delivery as the primary activity of
postal workers; thus, choice B is inappropriate. Because the passage explicitly ascribes productivity to entire
categories of workers, choice C is inappropriate. Choice E is inappropriate, since the objector does not question
the relevance of the number of letters delivered but implies that something else might also be relevant.

15. The information in choice B says that young bowerbirds progress slowly toward mastery of a bower-building
style, which suggests that the skill is one they must learn, rather than one whose transmission is wholly genetic.
Choice B also suggests a means of cultural transmission, namely, observation of older birds’ technique. Thus, B
supports the conclusion and is the best answer.
That differences within building styles are outnumbered by similarities (choice A) and that local populations have
little contact (choice D) are both equally consistent with building-style differences being culturally acquired or
genetically transmitted. Nor are differences among species of bowerbird (choice C) the issue. Finally, choice E
confirms the possibility of birds leaning skills, but it is not evidence that bower-building styles are learned.

16. The conclusion is based on comparing newspaper sales in Town S and Town T. Four answer choices indicate
why greater newspaper sales in S need not imply that citizens of S are better informed about world events.
Choice B suggests that many newspapers sold in S inform citizens of T, not S. Choices A and C both show how
greater newspaper sales can occur without the average citizen having greater familiarity with the news. Finally,
choice D suggests that much newspaper reading in S is not a source of information about world events. The price differential noted in E might help to explain the difference in sales, but it does not undermine the conclusion based on that difference. Therefore, E is the best answer.

17. If the ibora can be successfully cultivated, it is possible to continue production of the drug without threatening the
ibora with extinction. Therefore, choice D is the best answer.
If production continues, the method for distributing the drug aftr it has been produced (choice A) is not likely, on its own, to have consequences for the continued existence of the ibora. Nor is the price of the drug (choice B). If the leaves of the ibora also have a use (choice C), the threat of extinction is strengthened rather than weakened. Finally, if the ibora is largely inaccessible (choice E), this bears on the question of whether production of the drug could continue, not on what would happen if it did continue.

18. Farmers benefit from governmental price supports only when they produce the same crops from year to year. Farmers who wish to receive the benefit of these price supports will be unlikely to reduce water pollution
because they will not follow the experts’ advice regarding diversification and rotation. Thus, A is the best answer.
Since the experts’ advice is evidently their favored solution, the notion that the sole solution is something else (choice B) is not supported. The statements mention neither farmers' costs and revenues nor development in farming techniques, and thus support no conclusions about prospects for profits (choice C) or future farming techniques (choice D). Because no information is given about either the amount of price support or farmers debt, choice E is not supported.

19. According to choice B, the effect of lowering wages is to reduce quality sufficiently to reduce sales. This is a good reason to doubt that wage cuts would give Shelby Industries any competitive advantage, so choice B is the
best answer.
Some of the other choices provide good reasons for, rather than against, lowering wages. Choice A implies that
reducing the cost of raw materials is not possible, choice D indicates that Shelby Industries’ wages are relatively
high, and choice E suggests that Shelby Industries would not lose many workers if it did reduce wages. Choice
C gives a reason for Shelby Industries to be concerned about its competitive position but no reason to think
wage cuts would not improve that position.

20. If many residents of these communities host visiting grandchildren several weeks a year, as D states, that in
itself might generate sufficient demand for rented children’s furniture to support thriving businesses. Thus, D
helps reconcile the apparent discrepancy and is the best answer.
The few households mentioned in choice B are unlikely to generate sufficient demand for rental businesses to
thrive. Similarly, choices A and E, though they provide information concerning the furniture that is rented in these communities, do not address the prior issue of why there should be such demand for children's furniture. Choice C helps explain why these communities have an unusually high demand for rental furniture, but not why such a demand would extend to children's furniture.

CR Questions 1 - 10

1. Many institutions of higher education suffer declining enrollments during periods of economic slowdown. At two-year community colleges, however, enrollment figures boom during these periods when many people have less money and there is more competition for jobs.

Each of the following, if true, helps to explain the enrollment increases in two-year community colleges described above EXCEPT:

(A) During periods of economic slowdown, two-year community colleges are more likely than four-year colleges to prepare their students for the jobs that are still available.

(B) During periods of economic prosperity, graduates of two-year community colleges often continue their studies at four-year colleges.

(C) Tuition at most two-year community colleges is a fraction of that at four-year colleges.

(D) Two-year community colleges devote more resources than do other colleges to attracting those students especially affected by economic slowdowns.

(E) Students at two-year community colleges, but not those at most four-year colleges, can control the cost of their studies by choosing the number of courses they take each term.

Question 2-3 are based on the following

Hardin argued that grazing land held in common (that is, open to any user) would always be used less carefully than private grazing land. Each rancher would be tempted to overuse common land because the benefits would accrue to the individual, while the costs of reduced land quality that results from overuse would be spread among all users. But a study comparing 217 million acres of common grazing land with 433 million acres of private grazing land showed that the common land was in better condition.

2. The answer to which of the following questions would be most useful in evaluating the significance, in relation to Hardin’s claim, of the study described above?

(A) Did any of the ranchers whose land was studied use both common and private land?

(B) Did the ranchers whose land was studied tend to prefer using common land over using private land for grazing?

(C) Was the private land that was studied of comparable quality to the common land before either was used for grazing?

(D) Were the users of the common land that was studied at least as prosperous as the users of the private land?

(E) Were there any owners of herds who used only common land, and no private land, for grazing?

3. Which of the following, if true and known by the ranchers, would best help explain the results of the study?

(A) With private grazing land, both the costs and the benefits of overuse fall to the individual user.

(B) The cost in reduced land quality that is attributable to any individual user is less easily measured with common land than it is with private land.

(C) An individual who overuses common grazing land might be able to achieve higher returns than other users can, with the result that he or she would obtain a competitive advantage.

(D) If one user of common land overuses it even slightly, the other users are likely to do so even more, with the consequence that the costs to each user outweigh the benefits.

(E)There are more acres of grazing land held privately than there are held in common.

4. In tests for pironoma, a serious disease, a false positive result indicates that people have pironoma when, in fact, they do not; a false negative result indicates that people do not have pironoma when, in fact, they do. To detect pironoma most accurately, physicians should use the laboratory test that has the lowest proportion of false positive results.

Which of the following, if true, gives the most support to the recommendation above?

(A) The accepted treatment for pironoma does not have damaging side effects.

(B) The laboratory test that has the lowest proportion of false positive results causes the same minor side effects as do the other laboratory tests used to detect pironoma.

(C) In treating pironoma patients, it is essential to begin treatment as early as possible, since even a week of delay can result in loss of life.

(D) The proportion of inconclusive test results is equal for all laboratory tests used to detect pironoma.

(E) All laboratory tests to detect pironoma have the same proportion of false negative results.

Questions 5-6 are based on the following.

In many corporations, employees are being replaced by automated equipment in order to save money. However,many workers who lose their jobs to automation will need government assistance to survive, and the same corporations that are laying people off will eventually pay for that assistance through increased taxes and unemployment insurance payments.

5. The author is arguing that

(A) higher taxes and unemployment insurance payments will discourage corporations from automating

(B) replacing people through automation to reduce production costs will result in increases of other costs to corporations.

(C) many workers who lose their jobs to automation will have to be retrained for new jobs

(D) corporations that are laying people off will eventually rehire many of them

(E) corporations will not save money by automating because people will be needed to run the new machines

6.Which of the following, if true, most strengthens the author's argument?

(A) Many workers who have already lost their jobs to automation have been unable to find new jobs.

(B) Many corporations that have failed to automate have seen their profits decline.

(C) Taxes and unemployment insurance are paid also by corporations that are not automating.

(D) Most of the new jobs created by automation pay less than the jobs eliminated by automation did.

(E) The initial investment in machinery for automation is often greater than the short-term savings in labor costs.

7. The sustained massive use of pesticides in farming has two effects that are especially pernicious. First, it often kills off the pests' natural enemies in the area. Second, it often unintentionally gives rise to insecticide-resistant pests, since those insects that survive a particular insecticide will be the ones most resistant to it, and they are the ones left to breed.

From the passage above, it can be properly inferred that the effectiveness of the sustained massive use of pesticides can be extended by doing which of the following, assuming that each is a realistic possibility?

(A) Using only chemically stable insecticides

(B) Periodically switching the type of insecticide used

(C) Gradually increasing the quantities of pesticides used

(D) Leaving a few fields fallow every year

(E) Breeding higher-yielding varieties of crop plants

8. When a polygraph test is judged inconclusive, this is no reflection on the examinee. Rather, such a judgment means that the test has failed to show whether the examinee was truthful or untruthful. Nevertheless, employers will sometimes refuse to hire a job applicant because of an inconclusive polygraph test result.

Which of the following conclusions can most properly be drawn from the information above?

(A) Most examinees with inconclusive polygraph test results are in fact untruthful.

(B) Polygraph tests should not be used by employers in the consideration of job applicants.

(C) An inconclusive polygraph test result is sometimes unfairly held against the examinee.

(D) A polygraph test indicating that an examinee is untruthful can sometimes be mistaken.

(E) Some employers have refused to consider the results of polygraph tests when evaluating job applicants.

9. According to the new office smoking regulations, only employees who have enclosed office may smoke at their desks. Virtually all employees with enclosed offices are at the professional level, and virtually all secretarial employees lack enclosed offices. Therefore, secretaries who smoke should be offered enclosed offices.

Which of the following is an assumption that enables the conclusion above to be properly drawn?

(A) Employees at the professional level who do not smoke should keep their enclosed offices.

(B) Employees with enclosed offices should not smoke at their desks, even though the new regulations permit them to do so.

(C) Employees at the secretarial level should be allowed to smoke at their desks, even if they do not have enclosed offices.

(D) The smoking regulations should allow all employees who smoke an equal opportunity to do so, regardless of an employee’s job level.

(E) The smoking regulations should provide equal protection from any hazards associated with smoking to all employees who do not smoke.

10. Dental researchers recently discovered that tooth-brushes can become contaminated wth bacterial that cause pneumonia and strep throat. They found that contamination usually occurs after toothbrushes have been used for four weeks. For that reason, people should replace their toothbrushes at least once a month.

Which of the following, if true, would most weaken the conclusion above?
(A) The dental researchers could not discover why toothbrush contamination usually occurred only after toothbrushes had been used for four weeks.

(B) The dental researchers failed to investigate contamination of toothbrushes by viruses, yeasts, and other pathogenic microorganisms.

(C) The dental researchers found that among people who used toothbrushes contaminated with bacterial that cause pneumonia and strep throat, the incidence of these diseases was no higher than among people who used uncontaminated toothbrushes.

(D) The dental researchers found that people who rinsed their toothbrushes thoroughly in hot water after each use were as likely to have contaminated toothbrushes as were people who only rinsed their toothbrushes hurriedly in cold water after each use.

(E) The dental researchers found that, after six weeks of use, greater length of use of a toothbrush did not correlate with a higher number of bacterial being present.

Official answers and official explanations..

1. Choice B, the best answer, might explain the decreased enrollment at four-year colleges during the slowdown,but because it deals with graduates of two-year colleges it cannot explain why enrollment at these colleges might increase
Four of the choices give reasons why, in an economic showdown, many people would choose a two-year college.
Choice A indicates that a two-year college education gives one a better chance of finding a job when economic conditions are poor.
Choice C and E indicate why people with less money might prefer two-year colleges.
Choice D suggests that more is being done to attract people whose lives are affected by the slowdown to two-year than to four-year colleges.

2. Hardin’s claim is that common grazing land deteriorates more quickly than private grazing land because of overuse. The study indicates that common grazing land is currently in better shape, but this would not
undermine Hardin’s claim if common grazing land was in far better shape before grazing began. Thus, choice C is the best answer.
Choices A and E are inappropriate since the study can undermine Hardin’s Claim whether or not some ranchers use both sorts of land, or use only common land.
Similarly, the study can undermine Hardin’s claim whether or not ranchers prefer to use common land, as B says.
Finally, D is inappropriate since the force of the study is not
diminished if users of common land are more or less prosperous.

3. The study indicates that common lands are in better shape than private lands. The best answer, D, indicates that,
contrary to Hardin’s claim, it is in each rancher’s self-interest not to overuse common land, which would explain why common lands are in relatively good shape.
Choices A and C can only explain why private land is in better shape than common land, not the reverse.
Neither the fact that it is more difficult to attribute deterioration of common land to any particular user (choice B) nor the
fact that the relative amounts of common and private land differ (choice E) gives a reason for farmers not to graze their herds on common land as much as possible.

4. The most accurate test for pironoma would be the one with the fewest false results. If all tests have the same proportion of false negatives, then the most accurate is the one that has the lowest proportion of false positives. Thus, E supports the recommendation and is the best answer.
Choice A and C deal with the treatment for pironoma and are irrelevant to the accuracy of tests pironoma.
Choice B deals with the side effects of tests for pironoma, and does not address their accuracy.
That the proportion of inconclusive test results is equal for all tests (choice D) leaves open the question of which test is
more accurate, since it does not indicate which test has fewest false results.

5. The author argues that replacing employees with automated equipment might lend to less savings for corporations than anticipated, since laying off workers will lead to other costs. Choice B states the author’s main points and thus is the best answer.
The author argues that corporations that automate might incur unexpected costs, but the author does not argue that these costs will discourage corporations from automating (choice A).
The author does not address the issues of retraining (choice C) and rehiring (choice D).
Although the author argues that some unanticipated costs might offsets savings resulting from automation, the cost of running the new machines (choice E) is clearly not one of these unanticipated costs.

6. The threat envisioned by the author to the economic survival of workers displaced by automation will be serious only if they cannot find new jobs. Choice A, the best answer, says that there are already many such workers unable to find new jobs, and so strengthens the author’s argument.
Since the causes for declining profits for corporations that fail to automate are not analyzed in the passage, B is
inappropriate.
By saying that costs associated with unemployment C weakens the argument.
Since the author
tacitly grants that, initially, automation will cut costs, the detail given in D provides us added support.
Choice E is
inappropriate because it concerns short-term rather than long-term results of automation.

7. Choice B gives a way of counteracting a serious drawback of the sustained massive use of pesticides. By periodically changing the pesticide used, pests resistant to one pesticide might be killed by the next pesticide, and those resistant to that pesticide might be killed by another, and so. Therefore, B is the best answer.
Choice A is inappropriate, since the effects of stable pesticides would simply be more persistent.
Gradually increasing pesticide amounts (choice C) will likely have no effect on pests already resistant to massive amounts.
Leaving a few fields fallow (choice D) is not relevant to the effectiveness of sustained use of pesticides.
Breeding higher-yielding crops (choice E) might temporarily increase yields, but not because of anything to do with pesticides.

8. The passage indicates that an inconclusive polygraph test tells nothing about the person who has taken the test, and yet employers sometimes refuse to hire someone whose results from such a test are inclusive. Treating lack of information as if it were unfavorable evidence about a person can reasonably be considered unfair. There, C is the best choice.
Choice A is not supported, since the passage says that an inconclusive polygraph test is no reflection on the examinee.
Neither B nor D is supported, since the information given includes nothing either implicit or explicit about polygraph tests that yield conclusive results.
Since the passage is consistent with both E and its denial, E is not supported.

9. The regulations allow some employees-those with enclosed offices-but not others the opportunity to smoke at their desks. If it is assumed that the regulations should allow all employees equal opportunity to smoke, those who are currently denied this opportunity should be given it, and so secretaries who smoke should be offered enclosed offices. Therefore, choice D is the best answer.
None of the other choices enables the conclusion to be properly drawn. Choice A tends to conflict with the conclusion, unless some enclosed offices are vacant.
Choice B supports no conclusion about how secretaries should be treated, Choice C undermines the conclusion.
Finally, nonsmokers already have equal protection from hazards, so choice E cannot be used to justify making any changes.

10. According to choice C, using a contaminated toothbrush does not increase the incidence of infection, so the recommendation to replace a toothbrush before it becomes contaminated is greatly undermined. Choice C is therefore the best answer.
Since the recommendation is based on the discovery that bacterial contamination occurs after about four weeks, the researchers’ inability to discover why contamination takes that long to appear does not weaken the recommendation (choice A), nor does their failure to investigate other forms of contamination (choice B), nor does the discovery that contamination does not worsen after six weeks (choice E). According to choice D, even thorough washing cannot prevent contamination, so replacing the toothbrush appears more essential, rather than less so.