During the Korean War, the United Nations stepped in to support South Korea. By that same time, China and the Soviet Union had advised to not trespassed the 38th parallel because if that was made they would intervene in the war.
By October the UN forces overpass the parallel and that led China to become involved in the war with the help of the Soviet Union.
The correct answer is J The Japanese bombing of a U.S military base. The attack on Pearl Harbor on December 7, 1941 led to the U.S entering World War II.
