The u. s. applied which of the following policies to try and limit the spread of communism?
a. the "monopoly doctrine"
b. the "restriction plan"
c. the "domino theory"
d. the "nixon corollary"

The answer for this question is C. The Domino Theory. This theory states that if a country came under communist rule, its neighboring countries and regions would follow as well. This theory is what the US used as a reason to intervene in the different affairs of various countries to stop or prevent communism from spreading.