What caused the Gulf of Tonkin affair? a. American support for covert

What caused the Gulf of Tonkin affair?

a. American support for covert operations in Vietnam led North Vietnam to attack a U.S. ship.
b. American intervention in Cuban politics led Castro to urge the North Vietnamese to attack U.S. ships.
c. American hostility to Russia caused Khrushchev to ask the North Vietnamese to attack U.S. ships.
d. Russian hostility to North Vietnam caused Khrushchev to ask the United States to seize North Vietnamese ships.
e. North Vietnam attacked South Vietnamese ships carrying valuable natural resources to the United States, and the Americans retaliated.

ANSWER
A