What was the name of the theory that said that if one country in a region fell to communism, others would surely follow?
a. domino theory
b. arms race
c. brinkmanship
d. containment theory

The correct answer is: a.  domino theory   This effect also receives the name of snowball effect sequence, where if a country enters a certain political system, it would take others with it to that same system. It is believed that the emergence of this term is due to the American Eisenhower who said that communism could spread throughout the world.

they died because of a disease during the first spanish colonies.