Answer:
D. Each region established its own ''iron curtain'' to protect its interests
Step-by-step explanation:
After the World War II, Western and Eastern Europe quickly diverged because of their politics. While the West was promoting democracy and market economy, the East was promoting communism and command economy. The strategic interests were intermingled, which led to lot of tensions, so there was a sharp division with artificial political boundary that was separating the two. As both sides were trying to spread their ideologies, but were also afraid of the influence of their opponent, they set ''iron curtains'' resulting in isolation between the two on pretty much every level.