The “suicide wave” that followed the United States stock market crash

I'm seeing lots of back and forth on this question, so I feel inclined to give a response with solutions and my reasoning behind the correct answer choice. I hope this is of some benefit to my fellow GMATWarriors.

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The “suicide wave” that followed the United States stock market crash of October 1929 is more legend than fact. Careful examination of the monthly figures on the causes of death in 1929 shows that the number of suicides in October and in November was comparatively low. In only three other months were the monthly figures lower. During the summer months, when the stock market was flourishing, the number of suicides was substantially higher.

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

Pre-thinking the answer: The conclusion is that the suicide wave following the US stock crash of OCT 1929 is more legend than fact. The main premises are that OCT and NOV 1929 have low suicide rates relative to the rest of that year's month's, with the exception of three other months. If I am to challenge the conclusion, I need to demonstrate that the suicide wave is high relative to some other factor such as previous years' Octobers and Novembers. If I can show, for example, that the suicide rate for the months of October and November in the years 1920-1928 were far lower than those for October and November of 1929, I could sufficiently show that there actually was an increase in suicides in October and November of 1929, thereby challenging the conclusion that the suicide wave was practically a non-event.

(A) The suicide rate is influenced by many psychological, interpersonal, and societal factors during any given historical period.

Incorrect - While true, it is unhelpful in challenging the question as it lacks any sort of evidence to suggest that the particular months of October and November in 1929 actually had a relatively high suicide rate. Remember, we need to identify something very particular in order to challenge the conclusion. This answer choice is far too broad.

(B) October and November have almost always had relatively high suicide rates, even during the 1920s and 1930s.

Incorrect - This actually solidifies the stimulus's conclusion. This answer choice basically states that there was practically no change in the relative suicide rate for the months of October and November. We need to state the precise polar opposite (not to be confused with logical opposite).

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

Correct - Let's say that, for the years 1920-1928, there are an average of 100 suicides every July verses an average of 15 and 10 for the months of October and November, respectively. So if in October and November of 1929 there is an average suicide rate of 60 and 40, respectively, the average for the months of October and November are still relatively low in comparison to July's 100 suicides. If, however, all Octobers and Novembers for the years 1920-1928 had only 10 suicides each per year, but in 1929 had 60 and 40, respectively, then we suddenly see that the suicide wave was in fact something far beyond the typical. That is precisely what this answer choice does for us, and, thus, it is the correct answer choice. Choice C demonstrates that the suicide rate is in fact relatively high because the October and November average was far higher relative to those months during the 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 toward the end of that year.

Incorrect - Again, this actually supports the conclusion of the stimulus rather than challenge it.

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

Incorrect - This does not speak to the relative frequency that we are hoping to challenge. This answer choice is therefore irrelevant for our purposes.
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I'm not sure that this question should be labeled as 700. The language can trip people up, but it certainly feels more appropriate to the 600-650 range.

I hope my responses helped some of you out there.

~David