请教一道旧prep的题

ken178

Herbicides allow cereal crops to be grown very efficiently, with virtually no competition from weeds.In Britain, partridge populations have been steadily decreasing since herbicide use became widespread.Some environmentalists claim that these birds, which live in and around cereal crop fields, are being poisoned by the herbicides.However, tests show no more than trace quantities of herbicides in partridges on herbicide-treated land.Therefore, something other than herbicide use must be responsible for the population decrease.

Which of the following, if true about Britain, most seriously weakens the argument?

(A) The elimination of certain weeds from cereal crop fields has reduced the population of the small insects that live on those weeds and that form a major part of partridge chicks' diet.

(B) Since partridges are valued as game birds, records of their population are more carefully kept than those for many other birds.

(C) Some of the weeds that are eliminated from cereal crop fields by herbicides are much smaller than the crop plants themselves and would have no negative effect on crop yield if they were allowed to grow.

(D) Birds other than partridges that live in or around cereal crop fields have also been suffering population declines.

(E) The toxins contained in herbicides typically used on cereal crops can be readily identified in the tissues of animals that have ingested them.

这道题我在网上找不到解释，看来大家对这题都很明白，但是想了很久还是不明白。我是选D的。
我的疑问在于：这道题 要削弱的是Therefore, something other than herbicide use must be responsible for the population decrease这个结论，如果是的话选A那不是就是说的确有其它原因说明题目中要说的问题吗？要削弱结论就是要加强Some environmentalists 的claim不是吗？
想来想去还是不明白，脑子转不过来，麻烦各位CDER了

ken178

E选项是什么选项？支持S？？？

ken178

刚好看到就尝试解一下题。要削弱S的结论就要指出其问题。D选项没有说明任何问题啊。只是说W去了其它地方啊。我是这样想：去了其它地方会有可能是食物的问题，这种情况加强S，或者会有其它原因。这样情况削弱S。所以答案没有A好。个人观点，非NN。

小伊YSY

对于d选项我有很大疑惑阿……想起原来做的一道题
GWD3-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.

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.

当时这题我错选成d，答案是a
我就觉得这题和现在这题很类似，为什么这题里就不能选d了呢？

recoupsin

这是找隐含原因的。就是说不是C，而是A导致B，然而却是C导致A的。

liuconglei

对。A。

ken178

今天早上再重新看了这一道题，我做题的时候看来是没有看到第一句话。我想这题的解题思路应该是这样的：因为Herbicides allow cereal crops to be grown very efficiently, with virtually no competition from weeds.所以Herbicides把虫都KILL了，而PARTRIDGE这只鸟要吃虫，但是因为虫都被KILL了，所以就造成的PARTRIDGE这种鸟的数量减少。这样来削弱ARGUMENT。对吗？

typhoon_wang

D应该是无关?

A是指别的原因导致了PARTRIDGE 数量减少,而且这个原因并不是因为别的herbicide,所以是答案?

菜鸟一只,我的回答不作为答案