Answer:
D. Policy of Containment
Step-by-step explanation:
Containment was a United States policy using numerous strategies to prevent the spread of communism abroad. A component of the Cold War, this policy was a response to a series of moves by the Soviet Union to enlarge its communist sphere of influence in Eastern Europe, China, Korea, and Vietnam. The United States became involved in the Korean war was because Communism was spreading throughout China and they wanted to prevent that from happening.