Which of these was a cause of the korean war?
a) north korea established a blockade to prevent goods reaching south korea.
b) south korea entered into a treaty with china that endangered north korea.
c) north korea embraced communism while south korea chose democracy.
d) south korea rejected american policies supported by north korea.

C. A happened because of the war but the war happened because of C :)

 North Korea, led by a communist government, invaded south Korea. This was the immediate cause. It was seen as a communist attempt to Overtake an Allie of the US and therefore, caused the US to intervene. As well as 15 other nations which were part of the United Nations. So i would say the answer is C) North Korea embraced communism while South Korea chose democracy. 

We need to see the poster