The correct answer to this open question is the following.
Although there are no options attached we can comment on the following.
Considering the results of America cutting off aid to South Vietnam, should we have stayed longer?
No. It was just about time to withdraw the United States troops from South Vietnam.
Indeed, as many Americans think, the US should have never entered the Vietnam War. It was not a US war. However, as part of the policy of containment aimed to stop the spread of Communism around the world, the United States committed to help South Vietnam to fight against North Vietnam.
Let's have in mind that regarding a fast withdrawal, US President Richard Nixon thought that U.S. forces should NOT abruptly withdraw from Vietnam because South Vietnam would not be able to survive without U.S. help.
President Richard Nixon faced a dilemma during the Vietnam War years. After the Tate Offensive, many Americans in the United States started to question US Army participation in Vietnam. They thought that Vietnam was not an American War and the troops should be brought back to the US. On the other hand, the US had a political and economic interest in Vietnam trying to support South Vietnam to fight North Vietnam and contend the spread of Communism.