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.
This theory posited that if one country in a region fell to communism, neighboring countries would follow, like a row of dominoes falling over. As a result, the U.S. sought to contain the spread of communism through various means, including support for revolutions and independence movements that aligned with its interests.