The USSR blockaded all land routes to Berlin, causing the US and UK to pass the Berlin Airlift Act, which sent large amounts of food, supplies, and Christmas gifts to the people of Western Berlin over a couple of month's time. Admitting defeat, the USSR lifted the blockade ~12 months from the start.
Russia was blocking trade routes, because they didn't want other countries bringing aid to the people of West Berlin. the U.S wanted to do a more aggressive approach to the blockade, but Truman did not want to start another war. So, he ordered a massive airlift of aid to West Berlin. The planes took off from bases in England and Western Germany. ( A is the answer)
Not only does it give a sense of unity to these nations, but it is also beneficial to the people as well because they do not have to worry about exchange rates when traveling to other countries with the same currency.
