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 was a principle used during the Cold War suggesting that the spread of communism in one country could trigger a chain reaction of similar events in neighboring countries. The U.S. aimed to contain communism and prevent it from spreading, which often influenced its involvement in various revolutions and independence movements across the globe.