How Did the United States Respond When, in 1948, the Soviets

How did the United States respond when, in 1948, the Soviets blockaded Berlin, which was situated more than one hundred miles inside the Soviet zone?

A) It threatened to rescind the Allied agreement concluded at Yalta over the Soviet's role in Korea and Manchuria.
B) It cut off negotiations with Stalin over the Soviet Union's possible inclusion in the Marshall Plan.
C) It expelled Soviet diplomats from Washington, D.C., and mobilized U.S. forces in the American zone of occupation in western Germany.
D) It staged Operation Vittles, an ongoing airlift that supplied the residents of Berlin with food and fuel into the spring of 1949.