4. In which of the following ways was the Vietnam War different from previous wars for U.S. soldiers
A. The U.S. soldiers had the advantage of knowing their terrain.
b. The enemy employed guerrilla tactics that frustrated the U.S. soldiers.
c. The U.S. soldiers were fighting against the largest army they had ever faced.
d. The enemy had the same number of high-powered weapons as the U.S. military.