After the conference in Yalta and the agreement with Western Allies that Stalin had an influence and an interest zone in Eastern Europe, the Soviet Union began to establish, i.e. imposing communist regimes in the countries of Eastern Europe. The Western Allies have enabled fair and free elections in the Western countries and began to fear of the spread of Communism. In addition to the military NATO alliance and commitment to democracy, the West was a counterweight to Stalin, who formalized East European Alliance through the Warsaw Pact and created a counter-balance to the NATO.
The answer is: C.
