The correct answer is:
B. George Marshall.
George Catlett Marshall Jr. (1880–1959) raised through the United States Army to become Chief of Staff under presidents Franklin D. Roosevelt and Harry S. Truman. Then he served as Secretary of State and Secretary of Defense under Truman.
Winston Churchill lauded Marshall as the "organizer of victory" for his leadership of the Allied victory in World War II. Marshall guided the build-up of the U.S. Army from a force of little more than 200,000 in 1939 to a mobile army of more than 8 million soldiers and airmen that would fight around the globe during World War II.