These countries saw major changes in governance as a result of which action? eastern european revolutions of 1989 poland hungary east germany bulgaria czechoslovakia

It is true, the countries mentioned and the event mentioned constitute what is known as the Autumn of Nations, or the time period when Central and Eastern Europe freed itself from the Communist regime through a series of revolutions. The countries you mentioned switched to a capitalist scheme of running things instead of being a satellite state for the Soviet Union.