Among the choices, C is the best answer. It is because of the personal hostility of Woodrow Wilson and Henry Cabot Lodge, he opposes to compromise with Lodge. He fails to deliver a substantial appeal on behalf of the treaty.
The correct answer is C. a rise in isolationist sentiment in the United States
The US Senate was mostly controlled by the Republican party, which opposed the Democrat President Woodrow Wilson. Senators were divided into three groups: one block of Republican senators fiercely opposed the treaty, a second block of Democrats led by Woodrow Wilson that would only support a treaty with no reservations, and a third group, the largest one, that wanted a treaty with reservations. This third group posited that the treaty gave power to the new League of Nations to make war without the previous approval of the US Congress, which would eventually isolate the United States in international matters. The chances for ratification ended soon after President Wilson called Democrats to oppose the amendment, which led the polling to vote for the treaty or against it. For these reasons, the majority of the Senate voted against the treaty.
