The Chapter Introduction Juxtaposes the Stories of Marines in Vietnam

The chapter introduction juxtaposes the stories of Marines in Vietnam and National Guardsmen at Kent State to make what point?

A) Communist infiltration could harm Americans just as it did the South Vietnamese.
B) America divided over the fundamental question of who was a true friend and who the real enemy.
C) In the Vietnam War, the military was less the villain than the victim.
D) Poorly prepared and ineptly led armed forces led to America's defeat at home and abroad.