The 1920s was a period of economic prosperity for the united states as a result of

The correct answer is A) World War I.

The other options of the question were B) World War II. C) the Cold War. D) the Civil War.

The 1920s was a period of economic prosperity for the United States as a result of World War I.

Historians identify this prosperity in America after World War 1 with a term: "the Roaring 1920s." During this time, consumerism marked US Citizens' behavior. People bought everything they needed and wanted such as furniture, radios, or cars. The problem was that they mostly used credit to buy things. Years later, everything changed when the US stock market crashed on October 29, 1929, starting the period known as the Great Depression.

it would be  

germany had to pay all damages related to the war.

and i think

germany had to take sole responsibility for the war.