What was the incident where East Germany cut off West Berlin's access?

The correct choice highlights the Berlin Blockade, which was a crucial event during the Cold War. This incident occurred in 1948 when the Soviet Union, in an effort to exert control over Berlin, blocked all ground access to West Berlin. West Berlin was situated deep within East Germany and was a focal point of tension between the communist East and the democratic West.

The blockade aimed to force the Allied powers to abandon West Berlin, effectively isolating it from the rest of Germany. In response, the Allies organized the Berlin Airlift, a massive operation to supply West Berlin with food, fuel, and other essential goods by air. This airlift demonstrated the commitment of the West to support West Berlin and resist Soviet pressure.

In contrast, the Berlin Crisis refers to the broader set of tensions surrounding Berlin during the Cold War, while the Berlin Conference pertains to the meeting in 1884-85 where European powers divided Africa among themselves, not related to Berlin's post-World War II situation. The understanding of the Berlin Blockade is vital, as it exemplifies the geopolitical struggles of the era and the methods employed by different powers during the Cold War.