The fear of nuclear war in postwar led the U.S. government launch of programs to investigate suspected communists.
Aftermath the Cold war, the United State had to investigate suspected spread of communism idea among its citizen.
Thus, this fear of spread of communism which will promote a nuclear war in postwar led the U.S. government launch of programs to investigate suspected communists.
Therefore, the Option D is correct
Read more about Cold war
brainly.com/question/25774915
#SPJ1