Answer:
D. The United States wanted to prevent communism from spreading.
Step-by-step explanation:
The Vietnam War was a long, expensive and disruptive attack that hollowed the communist government of North Vietnam against South Vietnam and its ally, the United States.
The contention was heightened by the continuous Cold War between the United States and the Soviet Union.
Restriction to the war in the United States harshly separated Americans, even after President Richard Nixon requested the withdrawal of U.S. powers in 1973. Socialist powers finished the war by seizing control of South Vietnam in 1975, and the nation was brought together as the Socialist Republic of Vietnam the next year.