The correct answers are A) Stocks were one way to make more money and C) People had a lot of extra money they didn't need.
During the 1920s, so many people heavily invested in the stock market because stocks were one way to make more money and people had a lot of extra money they didn't need.
During the decade of 1920, the United States lived a prosperous moment they called the "Roaring 1920s," where people had enough money to buy things needed or not. If they had bot enough cash they used credit. These good economic years made people ambitious and tried to get richer investing in the stock market where a lot of people had become rich investing in it.
