The correct answer is B. Truman Doctrine
Explanation
Truman Doctrine was an American politic plan that came up in the decade of the forties, created with the objective to give military support to the countries that were resisting against the foreign influence and most of the communist ideology. Its name is due to the American president Harry Truman who was the principal promoter of this politic. Additionally, in that time Greece and Turkey were in internal confrontations against communist which cause these were the first countries that received the military aid. So the correct answer is B. Truman Doctrine.