One weaken-question

The "suicide wave" that followed the US stock market crash of Oct 1929 is more legend than fact. Careful examination of the monthly figures on the causes of death in 1929 shows that the number of sucides in Oct and in Nov was comparatively low. IN only three other months were the monthly figures lower. During the summer months, when the stock market was flourshing, the number of suicides was substantially higher.

Which one of the following, if true, would best challenge the conclusion of the passage?

A) the suicide rate is influenced by many psychological, interpersonal, and social factors during any given historical period.

B)Oct and Nov have almost always had realatively high suicide rates, even during the 1920s and 1930s.

C) The suicide rate in Oct and Nov of 1929 was considerably higher than the average for those months during several preceding and following years.

D) During the years surrounding the stock market crash, suicide rates were typically lower at the beginning of any calendar year than twoard the end of that year.

E) Because of seasonal differences, the number of suicides in Oct and Nov of 1929 would not be expected to be the same as those for other months.

答案选C,请问推理过程是怎样的？

为什么不可选A? 用他因削弱不行吗？

MM注意：原文的结论是stock market crash 不是the number of sucides 多的原因，A选项支持而不是削弱这个结论。

原文说：1929年十月、十一月（stock market crash ）相比较于夏季（stock market was flourshing），the number of sucides 要低，结论是stock market crash 不是the number of sucides 多的原因。

削弱前提（十月、十一月的the number of sucides低），得选项C