How Did Truman Manage to Break the Blockade That Was

How did Truman manage to break the blockade that was initiated by Stalin in West Berlin?

A) He ordered an airstrike on the blockade.
B) He threatened to use nuclear force against the Soviet Union.
C) He publicly upbraided Stalin for his mistreatment of the East Berliners.
D) He appealed to the U.N. for help in resolving the crisis.
E) He authorized an airlift of food and supplies to Berlin for eleven months.