ff-21 need some help

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.

The answer is B

I wonder why answer is B rather than C.

Can somebody explain why b is answer for me ?

Thank you!

There should be 2 assumptions to support the hypothesis. The 1st assumption of the author is that only venereal disease will be treated by mercury in Beethoven’s time. The 2nd assumption is only some people in Beethoven's time will ingest mercury, if all people ingest mercury, the evidence is not useful. So, some people in Beethoven's time did not ingest mercury. The answer should be B.

A, E have nothing to do with the argument.

C is not necessary, 'Since mercury was commonly ingested in Beethoven’s time to treat venereal disease' is enough.

D is wrong:  according to the author, it is the venereal disease that will cause the deafness, not the mercury poison.

B是特称否定, 其矛盾关系为全称肯定. 即, 将B取非后就是 Everybody ingested mercury. 所有人都吃mercury, 那就说明不了问题了. 所以B是答案.

C: 原文已经说了mercury was commonly ingested in Beethoven’s time to treat venereal disease, 到底mercury有没有效和本题无关.

With your explanations, I finally understand why B is correct.

Thank for your help!  

who can explain that why A has nothing to do with the argument?

a说所有的水银都留在了体内，只能说明能体内的水银能检测出来，对文章的推理没有任何影响，他是作者默认的事实，不是原因，也不是结果

恩我觉得，A中是说 NOne of mercury can be eliminated。其实不一定要求none,只有有残余留在头发能够被检测出来就可以了。所以A不对。