各位求解一道题~

songxueer

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

Which of the following，if true，would best help explain how the sweetener mightproduce the observed effect?

(A) The government’s analysis of the artificialsweetener determined that it was sold in relatively pure form.
(B) A high level of the amino acid In the bloodinhibits the synthesis of a substance required for normal brain functioning.
(C) Because the sweetener is used primarily as afood additive，adverse reactions to it are rarely noticed by consumers.
(D) The amino acid that is a constituent of thesweetener is also sold separately as a dietary supplement.
(E) Subjects in the experiment did not know whetherthey were consuming the sweetener or a second，harmless substance.
答案是B  不懂B啥意思。。。各位大神帮忙解答下~~

maxwhite

lz,如果你看不懂这道题，其实完全可以用有关无关来解决。
原文大概是说有2组人做实验，一组人消耗大量的人工糖，另一组人不消耗糖。第一组人因此认知能力比第二组的人差。结论是因此糖中的一种氨基酸是主要原因。
问解释！！其实就是问糖（也就是氨基酸）如何使人的认知能力变差。。。
a: 政府认为这个糖是以纯形式卖的。（说的是糖是以什么形式卖的。无关）
b 大量的氨基酸在血液抑制了大脑正常运转需要的一种物质的合成。（说的是氨基酸的负作用，有关且方向一致）
c 糖主要用做事物添加剂，因为负作用很少被发现（说的是糖的用途，无关并且方向相反）
d 氨基酸也是一种事物补充剂（大概这个意思 说的是氨基酸的用途，无关）
e 人在实验中不知道是消耗了糖还是别的无害的物质 （无关！！）