After the loss and withdraw of American troops from South Vietnam in 1976 during the Fall of Saigon the Viet Cong pushed into Saigon and took control of South Vietnam. Thus ending the "war" and South Vietnam being reunited with the North under one communist government
The doctrine of popular sovereignty was used. That meant that people in those states could choose to vote to support slavery and since they were majority then slavery would be permitted. There were even states that were at first non-slave states but then things changed and they voted to introduce slavery into the state and people voted for this and supported this.
The answer would be: D, President Truman fired him for insubordination.
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