Conclusion: The suicide wave that followed the stock market crash is a myth.
Premise: Number of suicides in October & November 1929 were comparably low (compared to the rest of 1929). Only three months had lower rates.
Premise: During the summer months, when the stock market was thriving, the number of suicides was substantially higher. (Suggesting that the state of the stock market doesn't affect suicide rates.)
The question stem wants us to weaken the conclusion. In other words, it wants us to find evidence that the suicide wave actually did occur.
Answer choice B actually supports the conclusion that the suicide wave was a myth. If October and November suicide rates were usually relatively high during this time, why would they be relatively low immediately after the stock market crash? The passage tells us that they were relatively low in 1929, which means there were fewer suicides after the crash than normal. This means there was no suicide wave, which is why B is incorrect.
C is a better option. It seems that suicide rates vary by month. Some months have higher average rates than others. Even when the stock market was flourishing, the summer months had more suicides than after the stock market crashed. Maybe more people tend to commit suicide in the summer, regardless of the state of the stock market. If October and November 1929 had more suicides than the Octobers and Novembers of the surrounding years, this suggests something that could have been considered a "suicide wave."
