[原创]请教OG11-22 紫皮~

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Half of the subjects in an experiment-the experimental group--consumed large quantities of a popular artificial sweetener．Afterward，this group showed lower cognitive abilities than did the other half of the subjects-the control group．who did not consume the sweetener．The detrimental effects were attributed to an amino acid that is one of the sweetener's principal constituents，

 

22．  Which of the following，if true，would best support the conclusion that some ingredient of the sweetener was responsible for the experimental results?

(A)  Most consumers of the sweetener do not consume as much of it as the experimental group members did．

(B)  The amino acid referred to in the conclusion is a component of all proteins，some of which must be consumed for adequate nutrition．

(C)  The quantity of the sweetener consumed by individuals in the experimental group is considered safe by federal food regulators．

(D)  The two groups of subjects were evenly matched with regard to cognitive abilities prior to the experiment．

(E)  A second experiment in which subjects consumed large quantities of the sweetener lacked a control group of subjects who were not given the sweetener,

以上是题目，看懂了题目，可是不明白为什么选择d。看不太懂。请问d其实说什么？

另外，b和c是不是无关项，排除？

fingereleven

额。。其实就是说在试验前两个组的CA是一样的，试验后CA差异的原因是因为一组大量摄入了S。。。因此支持了结论：试验结果是由S中的某成分决定的。。

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谢谢楼上大大哦！

lovelylinny

属于assumption吗？