A. true.
The statement that Eisenhower, Kennedy, and Johnson all approved of the United States backing the South Vietnamese in their civil war is absolutely true. After the communist North Vietnam got her Independence in 1954, there began a civil war in South Vietnam. The communist insurgents backed by North Vietnam turned against the South Vietnam government. So US supplied its soldiers in South Vietnam to suppress the communist insurgents and the move was approved by Eisenhower, Kennedy, and Johnson.