[问题请教]Prep92

louisehu

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 the dense tree cover that formerly was a feature of most South American coffee plantations.

Scott:The population of the spruce budworm, the warbler's favorite 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 American 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 be only 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.

请问C为什么不对？我的理解是，C说明budworm的减少是暂时的，所以budworm的减少和songbird的减少没有必然联系，为什么不对呢？请牛人指教。谢谢！

sheryter

C说明budworm的减少是暂时的，以后可能会增加。但是以后的增加对过去事实的判断没有影响。

louisehu

哦，明白了，谢谢楼上！