What contributed to the economic boom of the 1920s in the United States? (1 ANew 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.
CThe 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.

A New manufacturing methods were applied to consumer goods after the country demobilized following World War I