The domino theory was:

A. If the Us could wipe out Soviet union then the rest of the communist countries would fall like dominoes

B. If S. Korea and S. Vietnam could remain democratic then that would inspire other countries to become democratic

C. If S. Vietnam fell into communist then the rest of Southern Asia will do so as well

D.) Id the U. S. aided war-torn countries then they would be able to over throw their communist ruler