请教GWD 15-13

答案C

但我选B， 因为如果other parts of the plants 的insecticide 比pollen多，那也许不是maize的insecticide造成的而是其他原因造成的（我觉得选项中these plants是指milkweed plants)

而如果成立，直接削弱argument: 是 maize 使 butterfly at risk

而C，，如果成立， 那还是maize 使 butterfly at risk,只不过少吃点或换个season吃就不会死了！

请指教， 不知道是不是说的过去

因为我们手里的GWD题的来源可能都不一样,为了避免浪费时间,请楼主把题目和选项贴上来,大家好讨论.

Certain genetically modified strains of maize produce a powerful natural insecticide. The insecticide occurs throughout the plant, including its pollen. Maize pollen is dispersed by the wind and frequently blows into milkweed plants tha tgrow near maize fields. Caterpillars of monarch butterflies feed exclusively on milkweed leaves. When these caterpillars of monarch butterflies are fed milkweed leaves dusted with pollen from modified maize plants, they die. Therefore, by using genetically modified maize, farmers put monarch butterflies at risk.

Which of the following would it be most useful to dertermine in order to evaluate the argument.

A. Whether the natural insecticide is as effective against maize-eating insects as commercial insecticides typically used on maize are

B.Whether the pollen of genetically modified maize contains as much insecticide as other parts of these plants

C. Whether monarch butterfly caterpillars are actively feeding during the part of the growing season when maize is releasing pollen.

D. Whether insects that feed on genetically modified maize plants are likely to be killed by insecticide from the plant's pollen

E. Whether any maize-eating insects compete with monarch caterpillars for the leaves of milkweed plants growing near maize fields

I have changed my mind, C looks better, as the argument is maize's insecticide==> caterpillars ==> as a result,butterflies at risk

C obviousley better