prep1-92

zhouyeying

Kate:  The recent decline in numbers of theTennessee warbler, a North American songbird that migrates each fall to coffeeplantations in South America, is due to theelimination of the dense tree cover that formerly was a feature of most SouthAmerican coffee plantations.
Scott:  The population of the spruce budworm, thewarbler's favorite prey in North America, hasbeen dropping.  This is a more likelyexplanation of the warbler's decline.
Whichof the following, if true, most seriously calls Scott's hypothesis into question?
A.The numbers of the Baltimore oriole, a songbird that does not eat budworms butis as dependent on South American coffee plantations as is the Tennesseewarbler, are declining.
B.The spruce budworm population has dropped because of a disease that can infectbudworms but not Tennessee
warblers.C.The drop in the population of the spruce budworm is expected to be onlytemporary.
D.Many Tennessee
warblers have begun migrating in the fall to places other than traditionalcoffee plantations.E.Although many North American songbirds have declined in numbers, no otherspecies has experienced as great a decline as has the Tennessee warbler.
答案为A
我选的C

zhouyeying

明白了，谢谢

youngerlee

In weakening type questions, you use information from the answer choices to provide counter evidence against the stated conclusion.  You do not need to kill the original argument.  Neither can you use outside information beyond what is stated in the stimulus and the answer choices.

Answer (A) is  a direct attack on Scott's idea that budworms are the source of the problem because answer (A) provides an example that a species that doesn't eat budworms (or, to put it another way, is not affected by the cause of change proposed by Scott) also experienced exactly the same decline. Therefore, answer (A) adds more credibility to Kate's theory and, at the same, casts more doubts on Scott's hypothesis.