What Was the Basic Premise of the Domino Theory?​

What was the basic premise of the domino theory?​

A) The spread of communism would eventually result in mutually assured destruction.
B) If one state in a region fell to communism,the surrounding countries would fall as well.
C) ​The free world had to line up its military,economic,and political power with that of the Soviet Union.
D) ​Working together with the Soviet Union and other communist countries on peaceful endeavors was the best way to avoid war.