Which of the Following Was One of the Contributing Causes

Which of the following was one of the contributing causes of the stock market crash of October 1929?

A) For years, Americans were far too cautious in their spending and investments.
B) The gap decreased between production levels and the ability of the public to consume.
C) Decline of labor unions removed a check on rapid business growth.
D) Competition from foreign companies drove businesses under and lost many people their jobs.
E) The agricultural industry was by far the most stable, while other industries had stagnated.