Answer:
A is the correct option.
Step-by-step explanation:
The Korean war started on 25th June 1950. It started when the North Korean army crossed the 38th parallel. The 38th parallel was the boundary between Southern Korea which was the Republic of Korea and northern Korea which was the Democratic Peoples Republic of Korea. The north was back by USSR and the south was backed by the US. The invasion of the south was the first military action during the cold war. The USSR and the US both entered the war on each other's behalf. The war came to an end on July 1953. At least 4.5 million civilians lost their lives.The Korean peninsula remained divided after the war.