Answer:
The United States used B.) Military Force/Intervention.
Step-by-step explanation:
The conflict escalated into warfare when North Korean military (Korean People's Army, KPA) forces—supported by the Soviet Union and China—crossed the border and advanced into South Korea on 25 June 1950. The United Nations Security Council authorized the formation of the United Nations Command and the dispatch of forces to Korea to repel what was recognized as a North Korean invasion. Twenty-one countries of the United Nations eventually contributed to the UN force, with the United States providing around 90% of the military personnel.