21. Historian: We can learn about the medical history of individuals through chemical analysis of their hair. It is likely, for example, that Isaac Newton’s psychological problems were due to mercury poisoning; traces of mercury were found in his hair. Analysis is now being done on a lock of Beethoven’s hair. Although no convincing argument has shown that Beethoven ever had a venereal disease, some people hypothesize that venereal disease caused his deafness. Since mercury was commonly ingested in Beethoven’s time to treat venereal disease, if researchers find a trace of mercury in his hair, we can conclude that this hypothesis is correct.

Which one of the following is an assumption on which the historian’s argument depends?

(A) None of the mercury introduced into the body can be eliminated.

(B) Some people in Beethoven’s time did not ingest mercury.

(C) Mercury is an effective treatment for venereal disease.

(D) Mercury poisoning can cause deafness in people with venereal disease.

(E) Beethoven suffered from psychological problems of the same severity as Newton’s.

请问这题为什么选B啊？ 我觉得B是削弱嘛

B means that ingesting mercury is not the common behaviour by most of the people in B's time.

If almost all of the people ingest mercury ,the couclusion which only focus on the medical treatment that cater to special number of people became an unconvinced ones.

不好意思  还是不太理解

能用中文 解释一下吗？

前提（事实）1 ：调查头发中的化学元素能够帮助研究个人的用药史。

前提（事实）2 ：Beethoven可能有venereal disease(这词儿就不翻了，竟然这样说我很崇拜的人......)

假设：  mercury在B时代被广泛用于V disease   ----〉 可能是V  disease导致的B失聪。

逻辑推理：  如果B的头发中含mercury，假设成立。

感觉这道题目前提，假设，推理错综复杂，不容易直接找到原文中的逻辑瑕疵。

Assumption用取非，如果B取非的话，所有人在B那个时代都摄入Mercury，所有当时的人头发里面可能都含有Mercury，不能用此判断含有Mercury的人就是得了V disease的人，也就不能得出是V  disease导致的B失聪。