Which of the following statements about the American Expeditionary Force (AEF) is true?

A. The AEF broke the stalemate in favor of the Allies.
B. Due to the lateness of its arrival in Europe, the AEF saw relatively little combat.
C. Because of its inexperience, the AEF proved largely ineffective in combat.
D. The AEF had to be supported by the British troops.