By July of 1950, North Korean forces had pushed South Korean forces as far south as Pusan. The last option provided is correct.
In June 1950 communist North Korea overran South Korea. On June 25, 1950, North Korea launched a surprise attack on South Korea across the 38th parallel. Immediately, the North Korean army invaded South Korean.
The United States provided support and aided South Korea at the head of a United Nations force made up of more than a dozen countries.
