What foreign policy did the Truman Doctrine stand for during the post-World War II years?

A.) The United States would come to the aid of any Communist nation that wanted to switch to a democratic system.
B.) The United States would aid all free nations struggling against communism.
C.) The United States would not involve itself in European affairs as long as Europe stayed out of the Americas.
D.) The United States would give financial aid to any nation regardless of its form of government.