(A) President Woodrow Wilson was against the idea.
(B) ** the USA government was against the idea.
(C) the other countries did not allow USA to join.
EXPLANATIONS BELOW
Concept note-1: -Overview. The League of Nations was established at the end of World War I as an international peacekeeping organization. Although US President Woodrow Wilson was an enthusiastic proponent of the League, the United States did not officially join the League of Nations due to opposition from isolationists in Congress.