Answer:
From his involvement in the Montgomery bus boycott in 1955 until his untimely death in 1968, King's message of change through peaceful means added to the movement's numbers and gave it its moral strength. The legacy of Martin Luther King Jr. is embodied in these two simple words: equality and nonviolence.
D) To fight the spread of communism.
Because of the Domino Theory they thought that if Vietnam fell into Communism, the whole region would follow. So therefore they wanted to support South Vietnam in order to contain Communism in Asia.