The Nye Committee hearings in the 1930s popularized the idea that a key factor leading the United States into World War I had been A. German aggression. B. the power vacuum caused by the decline of the Ottoman Turkish Empire. C. the need to protect American bank loans to the Allies (which were used to buy arms from U.S. manufacturers). D. the need to protect American overseas colonial possessions (which were threatened by German and Japanese expansion).

C. the need to protect American bank loans to the Allies 

The Nye Committee, officially known as the Special Committee on Investigation of the Munitions Industry, was a United States Senate committee chaired by Senator Gerald Nye. The committee conducted hearings from 1934 to 1936 to investigate the role of the munitions industry in the American decision to enter World War I. The investigation was prompted by growing sentiment for isolationism after the war. The committee's findings suggested that the war had brought enormous profits to arms manufacturers, leading to the cynical view that these financial interests had effectively manipulated the U.S. into joining the conflict to protect their loans and arms sales. This perspective on World War I contributed to the passing of the Neutrality Acts in the 1930s and influenced American public opinion and policy up until the attack on Pearl Harbor in 1941.