Match the events that contributed tot the fall of the soviet union with the years in which they took place?

If your choices are the same as I've seen elsewhere here are your matches for the events shown, listed by year:

I'll provide a few more details on that last item, regarding Czechoslovakia.  In January, 1968, the new leader in Czechoslovakia, Alexander Dubcek, launched the "Prague Spring" (as it became known).  He sought to give communism "a human face," as he termed it, introducing many political and economic reforms.  By August, the USSR responded by sending in 600,000 troops, and again those Soviet tanks.  The revolution was put down.

But the Soviet Union's grip in Eastern Europe weakened over the next two decades.  By 1989, a number of Eastern European nations began to upend the communist governments that had held control in their countries.  The Berlin Wall was torn down during that time also.

other sources of text

explanation:

this can be magazines, news reports, scholarly articles, textbooks, research papers etc.

i would go with the last one