Which combination of factors contributed most to the start of the great depression of the 1930s?

Here are a list of factors that contributed to the start of the Great Depression:

1) Stock Market Crash of 1929-This event resulted in hundreds of thousands of Americans losing a significant amount of money. Thousands lost their entire life savings due to poor investments and the rapid drop in price of several different stocks.

2) Buying on credit - American families started to buy items on credit. This meant that they would put a little down and pay off an item over an extended period of time. However, many families did not realize that the interest rate charged on buying these items made them more expensive over time.

3) Bank failures - Banks across the country ran out of money after a series of bad loans and inability to collect currency from these people who they loaned money to.