Answer:
A. President Kennedy and Johnson feared losing Vietnam to communism is the correct answer.
Explanation:
They supported South Vietnam under the policy of containment. They supported the corrupt government because they wanted to defeat the communist north and Vietcong. The US government considered it to be like domino, if southern Vietnam fell to communists, it would set of a chain reaction which will bring other countries under the influence of communism. Decolonization was another factor for supporting South Vietnam ,as new countries were gaining their independence, US, china and Russia considered them to be their potential allies and whether they were eligible for support or not depended on their government. Since South Vietnam was a non communist state it was obvious that US would support it.
