Use the list to answer the question.
1) east and west germans tear down the berlin wall.
2)estonia, latvia, and lithuania break away from the soviet union.
3)mikhail gorbachev implements economic and political reforms.
4)the soviet union dissolves.
which event occurred last?

a. east and west germans tear down the berlin wall.

b. estonia, latvia, and lithuania break away from the soviet union.

c. mikhail gorbachev implements economic and political reforms.

d. the soviet union dissolves.