The correct option is: D began an airlift designed to keep West Berlin supplied with goods.
The first idea of the western allies was to take the necessary goods by an armed convoy to Berlin, but the plan was not executed since such activities legally implied an armed invasion of the USSR, which could lead to a war. Instead, the United States Air Command decided to supply the city by air through the three legally established air corridors. The Berlin airlift (in German: Berliner Luftbrücke) began on June 25, 1948, with the landing of the first C-47 cargo plane at the Tempelhof airport in Berlin.
