How did the north vietnamese supply their troops and the guerrillas in south vietnam?

a. supplies were sent via the mekong river.
b. supplies were sent across the demilitarized zone.
c. supplies were sent via the h. o chi minh trail.
d. supplies were sent via the red river.

How does the supremacy clause of the u.s. constitution affect the states? o a. it requires each state to establish a supreme court. b. it declares that the federal government can take away state powers if necessary. o c. it allows state governments to overthrow the federal government if necessary. o d. it ensures that the u.s. constitution overrules each state constitution