What was the Berlin Airlift?

Aa successful attack by the Western Allies on the city of Berlin during World War II
Ba successful plan by the Western Allies to overcome Stalin's blockade of Berlin
Can unsuccessful attempt by the Western Allies to take East Germany from the Soviet Union
Dan unsuccessful plot by Stalin to take over all of Berlin after World War II

What was the Berlin Airlift?

Aa successful attack by the Western Allies on the city of Berlin during World War ...