The correct answer is B) Containment.
Containment is the policy of stopping communism from spreading into other countries. The US adopted this policy after World War II.
One of the reasons behind this policy was America's rivalry with the Soviet Union, which was a communist country. Along with this, the system of communist went against many American values. For example, a communist system revolves heavily around government involvement in the economy. This includes telling businesses what products to create and how much of it to create. The US, on the other hand, was more in favor of a free market economy which allows businesses and consumers to make their own decisions.
This policy of containment would result in the US getting involved in the Korean and Vietnam War.