The correct answer is D. NATO and the Warsaw Pact were two competing alliances during the Cold War. Cold War was a state of political and military tension between powers in the Western Bloc (US and its NATO allies) and Eastern Bloc (the Soviet Union and its allies in the Warsaw pact). The term "cold" is used because there were no direct conflict between the two superpowers. It is usually considered that the Cold War begun in 1947 and ended in 1991, with the fall of the Soviet Union and many other communistic regimes.
