Answer:
The answer is D.
Explanation:
The Korean War was the 1st battle of the Cold War, and 1st major proxy war fought between the US and a Soviet communist supported enemy. A proxy war occurs when one or more opposing powers instigates a war and then uses 3rd parties to fight on their behalf.
Cambodia, the murders were commited by the Khmer Rouge.
Maybe it means that there’s a difference between how much land they own or something. It says there was a difference between the amount of land they occupied and the amount of land they couldn’t control. So maybe they didn’t own/have a lot of land but there was a lot of land they couldn’t get to/take over etc. or maybe this situation could be vice versa so they have a ton of land but only a little isn’t “controlled” let me know if this helps sorry if it’s confusing I’m just guessing based on the context clues :)
Previous American policy had centred around Isolationism. They did not want to get involved in foreign affairs and believed they didn’t need to. With the Truman doctrine, they wanted to contain the spread of communism, so they were prepared to fight wars and become involved on global politics to prevent such from happening.