Why was U.S. President Wilson unsuccessful in his attempt to get Senate approval for the Treaty of Versailles?

aThe Senate urged greater U.S. involvement in the League of Nations.

bMany Republican Senators favored greater U.S. involvement in world affairs.

cMost of the Senators did not agree with the U.S. policy of isolationism.

dThe Senate felt the treaty would limit U.S. independence in world affairs.