The correct answer is D. NATO.
SALT stands for Strategic Arms Limitation Talks. It was a series of bilateral talks between the United States and the Soviet Union on the limitation of strategic nuclear weapons. The first SALT treaty, SALT I, was signed in 1972. The second SALT treaty, SALT II, was signed in 1979 but never ratified by the United States Senate.
NPT stands for Nuclear Non-Proliferation Treaty. It is an international treaty that aims to prevent the spread of nuclear weapons. The NPT was opened for signature in 1968 and entered into force in 1970.
CTBT stands for Comprehensive Nuclear-Test-Ban Treaty. It is an international treaty that bans all nuclear weapons tests. The CTBT was opened for signature in 1996 and entered into force in 2000.
NATO stands for North Atlantic Treaty Organization. It is an intergovernmental military alliance between 30 member states – 28 European countries, the United States, and Canada. NATO was founded in 1949 to counter the threat of the Soviet Union.
NATO is not related to disarmament because it is a military alliance that aims to defend its members against attack.