The correct answer is C) the Soviet Union.
The nation that was engaged in the Cold War with the United States was the Soviet Union.
The Cold War years where those years of permanent conflict between the United States and the Soviet Union after World War II. The USSR tried to spread Communism in many countries of the world as had already happened in Bulgaria, Hungary, Czechoslovakia, East Germany, Poland, and Romania. But the United States always tried to stop it. During those years, both countries also competed in the so.called arms race, in which both countries wanted to ahead of each other in the construction of nuclear weapons.