请各位NN指点一下
比如说下面的一题吧，有人用的是排除方法（GWD-3-38）直接作出的答案（我直接把paopao给出的排除方法转贴了过来），但是我很困惑，什么样的选项才识无关选项呢？
Q38:
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.无关
The drop in the population of the spruce budworm is expected to be only temporary.无关，补充信息 Many Tennessee warbler have begun migrating in the fall to places other than traditional coffee plantations.无关 Although many North American songbirds have declined in numbers, no other species has experienced as great a decline as has the Tennessee warbler.无关比较点BE选项无关我还是想得通（没有直接说明TW下降，在说其他的事）。可是CD无关我就想不通了。到底选项什么样的内容才算是无关的呢？请各位NN帮我说一下，谢谢：）
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