Which Statement Is Most Accurate

Which statement is most accurate?

A) Had the stock market not crashed in 1929,there would have been no business downturn in the early 1930s.
B) Whether or not the stock market crashed,we definitely would have had a depression anyway.
C) Had it not been for the speedy and powerful reactions of the administration of Herbert Hoover,the depression would have been much worse.
D) It was not until the massive arms build-up leading up to our involvement in World War II that we finally began to emerge from the Great Depression.