Question

By October of 1950, UN forces had pushed the North Koreans back to?

A) Pusan.
B) the Yalu River.
C) the 38th parallel.
D) Seoul.

Answer 1

I'd probably go with (B) the Yalu River. By October, UN forces had pushed past the 38th Parallel and into North Korea in the hopes of cutting off the escape of the their leadership.

Seoul is the South Korean capital, so by then, they were way past that along with Pusan (which is on the southern tip of South Korea). The Yalu River stood between the Koreas and China who, at that point, responded to the potential threat of invasion by intervening in the war and rolling back the UN in a massive human wave attack.