The United States involved in the Vietnam War to prevent the takeover of South Vietnam by communist North Vietnam.
Answer: Option (c)
Step-by-step explanation:
The U.S troops entered into the "Vietnam War" to prevent the communist activities and to help french in the war. Domino Theory was one of the reasons for the involvement of the U.S in the "Vietnam war".
This theory states that communism would spread if Vietnam became a communist. Nearly 16000 Americans were sent to Vietnam for supporting South Vietnam troops.