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?\no domino theory\no arms race\no brinkmanship\no containment theory
Answer
Brief Explanations:
The domino theory posited that if one country in a region became communist, neighboring countries would likely follow suit, similar to how falling dominoes knock over others in a row. Arms - race refers to competition in building up military weapons. Brinkmanship is a strategy of pushing a dangerous situation to the brink of disaster to gain an advantage. Containment theory aimed to stop the spread of communism by various means but not with the specific "fall - like - dominoes" concept.
Answer:
A. domino theory