The correct response is:
The domino theory describes the U.S. policy for stopping the Soviet Union from influencing other countries in which people were staging revolutions and independence movements.
The domino theory suggested that if one country fell to communism, others in the region would follow, much like a row of falling dominoes. This belief drove U.S. foreign policy during the Cold War, leading to interventions in various countries experiencing revolutions or independence movements to prevent the spread of communism.