Which of these BEST explains the presence of the United States in China at the start of the 20th Century?
A) The U.S. had helped Nationalists defeat the Communists there.
B) The U.S. wanted to ally with China to stop the spread of Japan.
C) The U.S. had won Pacific territories in the Spanish-American War.
D) The U.S. needed to secure trade with China for industrial resources.