PrepTest 142, Section 1, Question 19

What we’re looking for

Working the answers

• A
  Correct

  Being highly adaptable leads to thriving in the new environment; thriving leads to harm to existing species. This species caused no such harm, so the argument concludes it isn't highly adaptable. Highly adaptable plays the role of freezing, thriving plays the role of the plants dying, and harm plays the role of stopped blooming. The absent final result rules out the first condition through both links, just as in the original.

• B

  This begins with thriving leading to adaptability, then connects adapting with harm. But its conclusion is conditional: if there is no harm, the species hasn't adapted. It doesn't establish that an actual species caused no harm and then rule out the first condition, thriving. It stops at the middle idea and states another rule, unlike the original's conclusion about what happened last week.

• C

  Adapting well is presented as a requirement for adversely affecting existing species. The conclusion uses the absence of that requirement to rule out harm. That is a different arrangement from two links followed backward from a missing final result to the absence of the starting condition. The problem isn't the words 'only if'; it is the different relationship being used.

• D

  Harmful introductions should be avoided, and introducing species is said to cause harm, so the argument recommends avoiding introductions. It applies a rule about what to do when harm occurs. It doesn't use the absence of a final outcome to rule out an earlier condition through a two-step chain.

• E

  This recommends controlling the populations of introduced species because doing so can reduce a risk that is likely to arise. The rule against introducing damaging species and the method for reducing risk don't form the original's chain. The conclusion recommends a response to an expected event rather than ruling out a past event from its missing consequence.