In my opinion the state department which is one of the most important government departments, is thoroughly infested with communists

senator Joseph McCarthy

this statement is most significant in the context of

a world war 1

b world war 2

c the cold war

d the communist revolution

The correct answer is C. The Cold War.

The Cold War era was the time period after World War II in which the United States and Soviet Union fought for global power and influence. During this time America was scared that the Soviet Union, a communist country, would spread their political system to other countries around the world. This fear resulted in the US government doing everything they could to stop the spread of communism. This idea is known as containment.

This time period is when Joe McCarthy became famous for his claims that he knew about communists in the United States. The claim discussed in the question is one that Joe McCarthy made in 1950. This also explains why the House Un-American Activities Committee had an unprecedented amount of hearings during the course of the early 1950's.