what was the name of the theory that said that if one country in a region fell to communism, others would…

what was the name of the theory that said that if one country in a region fell to communism, others would surely follow?\n\ndomino theory\narms race\nbrinkmanship\ncontainment theory
Answer
Brief Explanations:
The domino theory posited that if one country in a region became communist, neighboring countries would follow suit, similar to how falling dominoes knock over others in a row. Arms - race refers to competition in building weapons, brinkmanship is a risky diplomatic strategy, and containment theory was about preventing the spread of communism but not with the "fall - like - dominoes" concept.
Answer:
A. domino theory