The correct answer is D) people and supplies from entering or leaving West Berlin.
The Soviet blockade of West Berlin in 1948 was designed to prevent people and supplies from entering or leaving West Berlin.
Joseph Stalin ordered the blockade of Berlin to impede the United States, France, and Great Britain to enter West Berlin.
After the Yalta Conference of 1945, the USSR was not happy with the agreements and the relationship with the western countries deteriorated so much. As all the roads and entries were blocked, the solution was to sent supplies via air. The plan was called the Berlin Airlift. Almost 700 planes served as means of transportation to offer help to West Germany for one year.