The correct answer is A. The major participants in the Korean War were North Korea, South Korea, the United States, and China.
The Korean War took place between 1950 and 1953. Its components were the Republic of Korea (or South Korea), supported by the armed forces of several countries commanded by the United States; and the Democratic People's Republic of Korea (or North Korea), supported by the People's Republic of China and the Soviet Union. The war was one of the earliest episodes of the Cold War. Finishing with more than 3 million civilians and almost 15% of the population of the dead north, it constitutes one of the bloodiest wars in history.
The transcontinental railroad was built in the 1800s to connect Council Bluffs, Iowa, with the San Francisco Bay and revolutionize transport in the U.S.
