What Was the Truman Doctrine in American Foreign Policy

What was the Truman Doctrine in American foreign policy?

A) The United States would "roll back" communism from Central Europe.
B) The United States would again isolate itself from European affairs.
C) The United States would provide financial support to Western Europe through the gold standard.
D) The United States would support people resisting subjugation by armed minorities or outside pressures.
E) The United States would build bases across Western Europe to confront a possible Soviet invasion.