Respuesta :
The event that preceded the 1989 revolutions in the former Warsaw-pact nations was D. Gorbachev made reforms in the Soviet Union.
Who was Gorbachev?
Mikhail S. Gorbachev was a Russian and former Soviet leader, who worked as the eighth and final leader of the Soviet Union.
Gorbachev reformed the Soviet Union using two policy planks, called perestroika (economic reforms and liberalization and glasnost (freedom of expression and information).
Thus, the event that preceded the 1989 revolutions in the former Warsaw-pact nations was Option D.
Learn more about Gorbachev's reforms at https://brainly.com/question/1321517