Kate: The recent decline in numbers of the Tennessee warbler, a North American songbird that migrates each fall to coffee plantations in South America, is due to the elimination of dense tree cover that formerly was a feature of most South American coffee plantations.
Scott: The population of the spruce budworm, the warbler's favourite prey in North America, has been dropping. This is a more likely explanation of the warbler's decline.
Which of 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 but is as dependent on South America coffee plantations as is the Tennessee warbler, are declining
(B) The spruce budworm population has dropped because of a disease that can infect budworms but not Tennessee warblers
(C) The drop in the population of the spruce budworm is expected to only be temporary
(D) Many Tennessee warblers have begun migrating in the fall to places other than traditional coffee plantations
(E) Although many North American songbirds have declined in numbers, no other species has experienced as great a decline as has the Tennessee warbler
Between A and D, I fell for D. I ignored A for the reason that "the answer choice cannot be that simple(A familiar trap)". Any special tips on identifying cases when the answers could be simple and straight forward?