Question

The major reason the United States became involved in the Korean War was the

Answer 1

Your best answer is D. The U.S. and its allies invaded Korea to prevent the spread of Communism—a policy known as "containment."

A is wrong. Korea has plenty of natural resources, but the U.S. did not invade for this reason and it was hardly worth it to fight a huge war to gain access to Korean natural resources when the U.S. had far easier ways to secure those same resources back home and through trade.

B is wrong because there was no war or threat of war between China and the Soviet Union, both of which were Communist countries who actually fought on the same side (secretly) during the Korean War.

C is wrong because Japanese expansion ended after World War II, which came before the Korean War. 

Ba-da-bing. D.