What contributed to the economic boom was of the 1920s in the United States?
A)new manufacturing methods were applied to consumer goods after the country demobilized following World War I.
B) rapid economic growth in Europe gave US businesses access to foreign investment and new consumer markets.
C) the government increased health and safety regulations to protect consumers from dangerous business practices.
D) new social programs such as government pensions for the elderly raised the standard of living for the less wealthy.