The correct answer is D) The US worried that if communism could not be contained, then countries would fall to it one by one, like dominoes.
During the Cold War, the policy of containment and the domino theory were related in that The US worried that if communism could not be contained, then countries would fall to it one by one, like dominoes.
During the Cold War Years after World War II, the Soviet Union wanted to spread Communism in many different parts of the World. The United States policy of Containment tried to stop that spread because it considered that once some countries fell into Communism, others would follow as in the Domino Effect.
In those years the Soviet Union already controlled Communist countries such as Poland, East Germany. Hungary, Bulgaria, Romania, and Czechoslovakia, and exerted heavy influence on North Korea, China, and Cuba.
