What led the Soviets to blockade West Berlin?

If memory serves me right none of the above. What was happening was everyone was trying to get in and stay in West Berlin. At one time it was okay to work there but after a while when the people saw that Socialism does work they started staying. The Soviets realized that their 'brains' were being drained so they put a stop to it. Many people were killed trying to escape into West Berlin. It got so bad that the US had to air lift in supplies to the city. Didn't you read all of this in your history books. Shame on those socialist teachers you had in grade school. Now you know why we need to get back to studying our history.