Answer:
The answer is Option A: The idea of mutually assured destruction prevented the Soviet Union from launching a nuclear attack on the United States.
Step-by-step explanation:
The Cold War is an example of what is called a nuclear peace, where the costs of a war would be unacceptably high for both sides. However, it is probably a misnomer to call this "peace" as both the Soviet Union and the United States engaged in many satellite wars during this time in order to increase their respective spheres of influence. This includes Korea and Vietnam where there was Russian support for one side and United States support for the other. There were also other struggles involving Russian involvement like Afghanistan, where the USA played a role in supporting the Afghan Mujahideen against the Soviets.