21. The initial causes of serious accidents at nuclear power plants have not so far been flaws in the advanced-technology portion of the plants. Rather, the initial causes have been attributed to human error, as when a worker at the Browns Mills reactor in the United States dropped a candle and started a fire, or to flaws in the plumbing, exemplified in a recent incident in Japan. Such everyday events cannot be thought unlikely to occur over the long run.

Which of the following is most strongly supported by the statements above？

（A） Now that nuclear power generation has become a part of everyday life, an ever-increasing yearly incidence of serious accidents at plants can be expected.

（B） If nuclear power plants continue in operation, a serious accident at such a plant is not improbable.

（C） The likelihood of human error at the operating consoles of nuclear power generators cannot be lessened by thoughtful design of dials, switches, and displays.

（D） The design of nuclear power plants attempts to compensate for possible failures of the materials used in their construction.

（E） No serious accident will be caused in the future by some flaw in the advanced-technology portion of a nuclear power plant.

22. There is a widespread belief that people can predict impending earthquakes from unusual animal behavior. Skeptics claim that this belief is based on selective coincidence： people whose dogs behaved oddly just before an earthquake will be especially likely to remember that fact. At any given time, the skeptics say, some of the world's dogs will be behaving oddly.

Clarification of which one of the following issues would be most important to an evaluation of the skeptics' position？

（A） Which is larger, the number of skeptics or the number of people who believe that animal behavior can foreshadow earthquakes？

（B） Are there means other than the observation of animal behavior that nonscientists can use to predict earthquakes？

（C） Are there animals about whose behavior people know too little to be able to distinguish unusual from everyday behavior？

（D） Are the sorts of behavior supposedly predictive of earthquakes as pronounced in dogs as they are in other animals？

（E） Is the animal behavior supposedly predictive of earthquakes specific to impending earthquakes or can it be any kind of unusual behavior？

23. Defendants who can afford expensive private defense lawyers have a lower conviction rate than those who rely on court-appointed public defenders. This explains why criminals who commit lucrative crimes like embezzlement or insider trading are more successful at avoiding conviction than are street criminals.

The explanation offered above would be more persuasive if which one of the following were true？

（A） Many street crimes, such as drug dealing, are extremely lucrative and those committing them can afford expensive private lawyers.

（B） Most prosecutors are not competent to handle cases involving highly technical financial evidence and have more success in prosecuting cases of robbery or simple assault.

（C） The number of criminals convicted of street crimes is far greater than the number of criminals convicted of embezzlement or insider trading.

（D） The percentage of defendants who actually committed the crimes of which they are accused is no greater fro publicly defended than for privately defended defendants.

（E） Juries, out of sympathy for the victims of crimes, are much more likely to convict defendants accused of violent crimes than they are to convict defendants accused of “victimless” crimes or crimes against property.

24. Many major scientific discoveries of the past were the product of serendipity, the chances discovery of valuable findings that investigators had not purposely sought. Now, however, scientific research tends to be so costly that investigators are heavily dependent on large grants to fund their research. Because such grants require investigators to provide the grant sponsors with clear projections of the outcome of the proposed research, investigators ignore anything that does not directly bear on the funded research. Therefore, under the prevailing circumstances, serendipity can no longer play a role in scientific discovery.

Which one of the following is an assumption on which the argument depends？

（A） Only findings that an investigator purposely seeks can directly bear on that investigator's research.

（B） In the past few scientific investigators attempted to make clear predictions of the outcome of their research.

（C） Dependence on large grants is preventing investigators from conducting the type of scientific research that those investigators would personally prefer.

（D） All scientific investigators who provide grant sponsors with clear projections of the outcome of their research receive at least some of the grants for which they apply.

（E） In general the most valuable scientific discoveries are the product of serendipity.

25. Police statistics have shown that automobile antitheft devices reduce the risk of car theft, but a statistical study of automobile theft by the automobile insurance industry claims that cars equipped with antitheft devices are, paradoxically, more likely to be stolen than cars that are not so equipped.

Which one of the following, if true, does the most to resolve the apparent paradox？

（A） Owners of stolen cars almost invariably report the theft immediately to the police but tend to delay notifying their insurance company, in the hope that the vehicle will be recovered.

（B） Most cars that are stolen are not equipped with antitheft devices, and most cars that are equipped with antitheft devices are not stolen.

（C） The most common automobile antitheft devices are audible alarms, which typically produce ten false alarms for every actual attempted theft.

（D） Automobile owners who have particularly theft-prone cars and live in areas of greatest incidence of car theft are those who are most likely to have antitheft devices installed.

（E） Most automobile thefts are the work of professional thieves against whose efforts antitheft devices offer scant protection