PrepTest 116, Section 2, Question 23

What we’re looking for

Working the answers

• A

  The finding about cancer in rats is being used as a warning supporting a ban. A instead describes it as the hazard the recommendation is aimed at preventing. The contrast with missing human research points toward concern about the chemical's possible effects on humans, not a proposal whose stated purpose is to prevent cancer in the research rats. D describes the finding's supporting role more accurately.

• B

  Cancer in rats isn't presented as a benefit of continuing to allow dioxin. It is the worrying result that supports banning it. B gets both the favorable description and its relationship to the recommendation wrong.

• C

  The toxicologist says comparable research probably will never be done on humans but gives no argument here for that prediction. We might imagine ethical or practical reasons, but the passage doesn't supply them. The rat finding supports the ban, not an explanation of why future human research won't happen.

• D
  Correct

  The finding gives the toxicologist a reason to recommend a course of action: completely banning dioxin. In plain terms, it is a premise supporting the conclusion. The lack of human research is acknowledged, but the toxicologist still thinks the rat result warrants action.

  Calling the finding support doesn't mean we have proved that dioxin causes cancer in humans. We're identifying how the author uses the evidence, not deciding that the evidence establishes every concern behind the recommendation.

• E

  The claim that similar research has never been done on humans is stated separately. Showing that a chemical caused cancer in rats doesn't tell us which human studies have or haven't occurred. The argument uses the rat finding to support what should be done about dioxin, not to establish that research history.