What event triggered the United States to issue the Truman Doctrine?

A) The Soviet Union's development of an atomic bomb

B) Britain's inability to assist governments in Greece and Turkey

C) Churchill's declaration that an iron curtain had fallen across Europe

D) The failure of the Marshall Plan to assist European economic recovery

C) Churchill's declaration that an iron curtain had fallen across Europe

Explanation:

The Truman Doctrine is an expression that designates a set of political and economic measures assumed by the American government of President Truman after the Second World War. With the end of World War II, Europe was destroyed and weakened politically and economically, with which emerged two world powers, the United States and the Soviet Union, which represented capitalism and socialism respectively. In Winston Churchill's phrase, an iron curtain divided Europe into two parts, capitalists and socialists - which should be fought. Following Churchill's declaration, the US government declared support for the anti-socialism initiative. The Truman doctrine aimed at preventing the expansion of socialism, especially in capitalist countries weakened by war. According to Truman, it was the US's duty to defend the world of the Communists. From then on, the Cold War began, which left the world bipolarized between the two regimes until the collapse of the Soviet Union in the early 1990s, when capitalism triumphed.