PrepTest 113, Section 2, Question 21

What we’re looking for

Working the answers

• A
  Correct

  Communities with modern power plants have lower rates of certain major illnesses. That's the favorable result, corresponding to lower rates of some cancers among people eating more produce. Nuclear power is the potentially risky feature, corresponding to pesticide residues.

  Now follow the leap. The favorable pattern occurs even where the plant is nuclear, so the author declares no increased health risk from living next to a nuclear plant. Why would a result about heart disease and cancer settle every possible health effect? Like the original, A uses a limited favorable finding to support a much broader assurance of safety. We don't have to know whether nuclear plants actually pose a risk to recognize that unsupported expansion.

• B

  This compares two strategies—exercise and dietary restriction—and declares one more useful for heart health. The evidence hasn't directly compared those strategies. That is different from using a favorable finding about a few illnesses to rule out health risks generally. The conclusion also narrows to heart health rather than expanding to all health risks.

• C

  There is a problem here, but the comparison changes more than the vehicle. The motorcycle riders received extensive instruction; the car drivers only passed a test. Better training could help account for the motorcycle group's lower accident rate without showing that motorcycles are inherently no riskier. Accident frequency also needn't settle the seriousness of an accident.

  Compare that with A's closer match: a lower incidence of specified illnesses, a potentially risky feature present in some cases, and a conclusion dismissing health risk overall. C's unequal training introduces a different central comparison.

• D

  Fewer microbes don't automatically settle every question about infection risk. But D keeps its conclusion focused on microbial illnesses, the kind of risk relevant to the evidence about microbes. It doesn't take a favorable finding about a limited set of illnesses and declare the object safe from health risks of every kind.

• E

  This compares the long-term health benefits of two alternatives and concludes that one can be forgone if the other is used. Whatever questions we might raise about that reasoning, it doesn't start with a decrease in a few named illnesses and expand that into freedom from health risks generally. The familiar words about fruits, vegetables and health don't reproduce our argument's structure.