Answer: A) the Senate feared that the League of Nations would supersede U.S. authority.
The Treaty of Versailles was the peace treaty that ended WWI. This treaty included a provision that advocated for the creation of the League of Nations, an international body and predecessor of the United Nations.
President Woodrow Wilson supported the treaty, but it still needed to be ratified by Congress. Congress opposed the treaty, in particular the creation of the League of Nations. One of its main opponents, Henry Cabot Lodge, drafted "14 reservations" (to match Wilson's 14 points) where he argued that the U. S. would be giving up too much power under the league. The treaty was never ratified.