Answer:
A) Soviet efforts to create communist governments in Eastern Europe after WWII.
Explanation:
In 1947, after Britain´s announcement that it would stop aiding the Greek government to fight a communist insurgency, the Truman administration stepped in and said it would provide assistance to Greece and Turkey, which was also facing a communist threat. Since that moment on, the USA would oppose Soviet Union´s efforts to support communist movements in Europe by providing economic, military and diplomatic assistance to countries under threat.