求助~ 新prep2-118

crystalbain

118.      

Which of the following most logically completes the passage?

A certain tropical island received food donations in the form of powdered milk for distribution to its poorest residents, who were thought to be malnourished.Subsequently, the rate of liver cancers among those islanders increased sharply.The donated milk was probably to blame:recent laboratory research on rats has shown that rats briefly exposed to the substance aflatoxin tend to develop liver cancer when fed casein, a milk protein.This result is relevant because __.



A. in the tropics, peanuts, a staple of these island residents, support a mold growth that produces aflatoxin

B.the liver is more sensitive to carcinogens, of which aflatoxin may be one, than most other bodily organs
C. casein is not the only protein contained in milk
D. powdered milk is the most appropriate form in which to send milk to a tropical destination
E. the people who were given the donated milk had been screened for their ability to digest milk


用排除法选了个A,但不懂A为什么正确，恳请牛人给讲一下啊~

ddwantsmba

一些热带岛屿收一切捐赠的奶粉分给营养不良的穷人。结果这些岛民的肝癌率大幅提高。这归咎于奶粉：实验表明老鼠在吃了c之后，会暴露于a，而后引发肝癌。而c就存在于奶粉中。这个实验结果在证明奶粉是主因上非常有价值，是因为？
A.这个岛的主要食物有花生，花生就促进c生长。
这个题实际上是加强。采取的是架桥法。A+C=肝癌。题干中有c了，有肝癌了，选项中中只要只要找到a就可以了

piggycandys

对的，就是一个等价关系

crystalbain

哦~这样啊
谢谢牛人~
我消化一下。。