Answer :
The United States Senate refused to ratify the Treaty of Versailles after World War I because many senators believed 4. the League of Nations could draw the United States into future wars. The US had only just recently begun to emerge from isolation in the Western Hemisphere and had just fought in a particularly deadly World War. As such, Senators were wary and ultimately rejected placing the nation in the League of Nations because of the fear that it would result in future conflict.
Correct answer: many senators believed (4) the League of Nations could draw the United States into future wars.
Context/detail:
The United States never joined the League of Nations, in spite of the fact that an organization such as the League of Nations was the signature idea of US President Woodrow Wilson. He had laid out 14 Points for establishing and maintaining world peace following the Great War (World War I). Point #14 was the establishment of an international peacekeeping association. The Treaty of Versailles adopted that idea, but back home in the United States, there was not support for involving America in any association that could diminish US sovereignty over its own affairs or involve the US again in wars beyond those pertinent to the United States' own national security. Because of its objections to membership in the League of Nations, the United States Senate refused to ratify the Treaty of Versailles.