Final answer:
The policy that supports free peoples resisting subjugation by armed minorities or outside pressures is the Truman Doctrine, introduced by President Truman in 1947 to counter the spread of Communism. The correct option is C.
Step-by-step explanation:
Truman Doctrine was established by President Harry S. Truman in 1947 when he declared the U.S. would provide political, military, and economic assistance to all democratic nations under threat from external or internal authoritarian forces, primarily aimed to counter Soviet geopolitical expansion during the Cold War.
The doctrine was a significant departure from the U.S. historical policy of isolationism and non-intervention, marking the country's active move into global politics, especially in support of countries that were at risk of falling under the influence of Communism.
Hence, Option C is correct.