单选题

Drug companies lose money when manufacturing drugs that cure those suffering from rare diseases because selling a drug to only a few people usually does not recoup manufacturing expenses．Therefore, a company manufacturing any of the drugs that cure those suffering from loxemia, an extremely rare disease, will undoubtedly lose money． Which of the following, if true, most seriously weakens the conclusion above？

A、 Several drugs that cure those suffering from loxemia also cure those suffering from very common illnesses．
B、 Most of those who contract loxemia also contract another illness concurrently
C、 Most of the drug companies that manufacture drugs that cure rare diseases do not manufacture drugs that cure loxemia.
D、 A sizable number of people are afflicted with one or another rare disease even though each rare disease afflicts only a small number of people．
E、 The larger the amount of a drug that is manufactured, the lower the manufacturing expense for each unit of the drug that is produced．

【正确答案】 A

【答案解析】