The correct answer is C. Cold War competition began between the U.S. and the Soviet Union right after the end of World War II, when its alliance unraveled.
The Cold War rivalry emerged following World War II as the two powers, the United States and the Soviet Union, found themselves ideologically and geopolitically opposed despite having been allies against Axis powers during the war. The wartime alliance began to deteriorate as conflicting interests and mutual distrust surfaced. Key events such as the disagreement over the future of Eastern Europe, the division of Germany, and the differing visions for post-war reconstruction highlighted the ideological divide between the capitalist West, led by the U.S., and the communist East, led by the Soviet Union. This conflict eventually manifested in a range of competitive actions, including military confrontations, political maneuvering, and a nuclear arms race, marking the beginning of the prolonged Cold War.