Which of the Following Was the Main Reason Why the United

Which of the following was the main reason why the United States became involved in the conflict between North and South Vietnam?

A) The United States supported South Vietnam because it feared the spread of communism throughout Southeast Asia.
B) The United States supported North Vietnam because it admired Ho's nationalist goals.
C) The United States felt it could be a neutral arbitrator in the region, since the United States had not been a colonial power in the region.
D) The United States became involved in order to get access to petroleum reserves off the eastern coast of Vietnam.