Which of the following statements about American expeditionary forces 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 inexperienced, AEF, proved largely ineffective in combat
D the AEF had to be supported by the British troops

A the AEF broke the stalemate in favor of the allies