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 dose 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 warbler 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.
给出正确答案A,但我认为正确答案是D A只是证明Kate可能正确,但是不能直接驳倒Scott 而D说明鸟只是去了除了农园的其他地方,也就证明不是猎物下降,可以直接驳倒Scott。
求热心人解!! |