Why did the united states support vietnam

A. Their leadership was the result of a popular election

B. it's administration was democratic and open.

C. South Vietnam had a stronger military.

D. it's government was anti-communist.

The answer is D) it's government was anticommunist

because the u. s was afraid of communism spreading to South Vietnam and to the rest of Asia. Keep in mind that China was already communist by 1949 and that communist had power over North Vietnam.