The answer is letter c. The Truman Doctrine. The Truman
Doctrine was known as an American foreign policy made to oppose the Soviet geopolitical
development during the Cold War. The Truman Doctrine was announced to the
congress by President Harry Truman, hence the name, which was on March 12, 1947
and developed even further on July 12, 1948, when President Truman promised to
oppose the Soviet threats to Greece and Turkey.