The answer is D: the events leading to the stock market crash of 1929.
Since the topic in the answer above is a historical matter, it would be logical and coherent to organize the exposition of the information and the facts in the paper in chronological order so as to properly explain the causes and events that led to the stock market crash of 1929, clearly elaborating on this latter one as an effect —or a correlation, dialectical or otherwise— of the former.