There were several causes that lead to the Cold War. The most important ideological conflict was that the Soviets believed in Communism and rest of the worl including United States of America disliked Communism. Soviets were against capitalism and the Americans were in favor of capitalism. The Soviets were also afraid of the nuclear bombs that United States possessed during that time and it was a grave security concern for the Soviets.
Option B sounds the best if an area or region of countries is already having a lot of tension against one another then this sounds more likely to start an arms race.
