What was the purpose of the Berlin Airlift?

1.) to supply West Berlin during a blockade by Joseph Stalin
2.) to blockade East Berlin to contain Joseph Stalin
3.) to blockade West Berlin to contain Joseph Stalin
4.) to supply East Berlin during a blockade by Joseph Stalin

The purpose of the Berlin Airlift was to supply West Berlin during a blockade by Joseph Stalin. Therefore, the correct answer is 1.) to supply West Berlin during a blockade by Joseph Stalin.