In the Chinese Civil War, the United States Followed Which

In the Chinese Civil War, the United States followed which policy?

A) It supported Mao Zedong because it was apparent that the Communists would win.
B) It strongly supported Chiang Kai-shek and the nationalists, even promising to use atomic weapons if necessary.
C) It gave limited military aid to the nationalists, but it refused to be drawn into the conflict.