C. The conferences divided Europe into democratic and communist zones of control.
This statement best explains the impact of the Yalta and Potsdam Conferences on the Cold War. The conferences resulted in agreements that effectively divided postwar Europe into spheres of influence, with Western democracies (led by the United States and the United Kingdom) controlling certain areas, while the Soviet Union established its influence over Eastern Europe, setting the stage for the ideological conflict that characterized the Cold War.