Why Did the United States Neither Sign the Versailles Treaty

Why did the United States neither sign the Versailles Treaty nor join the League of Nations?

A) Republicans under Henry Cabot Lodge made a series of amendments to the treaty, which Wilson and the Democrats rejected.
B) The United States was not a legal party to the peace treaty and already had signed nonaggression pacts with Canada and Mexico.
C) The Republican Party was heavily controlled by the so-called "irreconcilables," who would not agree to any peace treaty.
D) After Woodrow Wilson suffered a stroke during his speaking tour on behalf of the treaty, he was no longer able to sign the document.