Answer:
A. the Vietnam War
Explanation:
The domino theory was the basis for the United States strategy of containment, and the reason for the U.S. to enter the Vietnam War. The Vietnam War was a result of the national strategy of containment. The national strategy of containment demanded the U.S. stop communist aggression into the countries of Southeast Asia. This strategy was developed from a belief in the domino theory. The domino theory basically stated if one new country went communist in Asia then it would begin a chain reaction that would cause several more Southeast Asian countries becoming communist.
The South became more dependent on slavery, deepening the differences between the South and the North
It was known as the era of divided government neither party has consistently held on to the presidency
