How Successful Was Deterrence During the Cold War and How

How successful was deterrence during the Cold War and how well does it work in the war on terror?

A) It worked in the Cold War because it helped wipe out communism; it is working just as well in the war on terror by helping wipe out terrorism.
B) It hindered the spread of democracy in Western Europe during the Cold War; today it hinders the spread of democracy in the Middle East.
C) It worked in the Cold War because the nuclear threat made leaders on both sides cautious; it does not work in the war on terror because terrorists ignore retaliatory threats.
D) It did not work in the Cold War,as demonstrated by U.S.involvement in Korea and Vietnam; it is working well in the war on terror,as shown by the lack of military conflict with North Korea and Iran.