Arrange the events that led to the unification of germany in correct sequence

The person above was almost correct in sequence.

For PLATO users, it's:

1) "The Soviet forces constructed the Berlin Wall to prevent the escape of East Germans into West Germany."

2) "US president Ronald Reagan delivered a famous speech challenging Soviet leader Mikhail Gorbachev to tear down the Berlin Wall."

3) "Newly independent Hungary opened its border with Austria."

4) "East German leaders gave orders to open the gates of the Berlin Wall."

5) "The representatives of East and West Germany signed the Reunification Treaty."

north atlantic treaty organization.