Answer:
So in short, the domino theory is an idea that neighboring countries will be effected by that country’s political ideology. This is most commonly used in context of the cold war, when the United States and Russia were competing for either Communism or Capitalism to be the used type of economic system. The United States government wanted to get involved with the Vietnamese war because they were afraid that if the Northern Vietnamese won the war, that the Southern Vietnamese would become communist.
True...........................
Its the second one i think have it checked i might be wrong :)
A type of civilization called Harrapa