Answer:
The right answer is:
c. The Americans had advanced as far as the China-Korea border and the Chinese were worried about the security of their borders and a possible invasion.
Explanation:
The direct motive of the Chinese entering the Korean War (1950-53) to support their North-Korean communist brethren was fear of a US invasion. After getting the communist withdrawal from Seoul and pushing them far north, the US forces approached the Chinese border. The route they were following was similar to that followed by the Japanese when they invaded Manchuria. That was a very fresh memory for China that had just emerged from two decades of war, including 8 years of bitter fighting with the Japanese. For them, it was preferable to fight in foreign territory than in their own territory. Neither Kim Il-sung, the North Korean leader, nor Soviet leader Joseph Stalin had expected the strong American reaction to the northern invasion of the South. For China, getting involved was also an act of communist solidarity, but the main motive was a deep concern about security.
