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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.

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.