Under domino theory, if South Vietnam fell to communism, other nations in the region might also become communist.
<h3>What is the domino theory?</h3>
A domino theory refers to a cold war policy that suggests that if one state adapts to communism then the neighboring states might also start adapting to commnism. The theory sees the states as a perfectly aligned row of dominos.
If South Vietnam fell to communism, it is likely that the neighboring states such as Laos, Cambodia, and so on might become communist.
Therefore, the correct option is B.
Learn more about domino theory here:
brainly.com/question/935467
