Final answer:
The correct event relating to the opposition leading to a significant political change is The Velvet Revolution, during which the dissident playwright Vaclav Havel became the President of Czechoslovakia, demonstrating a shift from authoritarianism to a democratic governance option (a).
Step-by-step explanation:
Among the options provided regarding those who stood out in opposition to the new mission of democratic change in Eastern Europe during the revolutions of 1989, the accurate statement is that The Velvet Revolution took place; a dissident playwright became president.
Specifically, Vaclav Havel, a Czechoslovakian playwright known for his opposition to the Communist regime, later became the President of Czechoslovakia following the peaceful demonstrations of the Velvet Revolution.
This transformative period marked by a series of democratic uprisings not only overthrew existing Communist governments but also symbolized the shift of power away from authoritarian rule and towards democracy, with intellectuals and dissidents emerging as significant political figures.
The Velvet Revolution stands out as a relatively bloodless change of regime that transformed not only Czechoslovakia but also inspired similar peaceful transitions throughout Eastern Europe, including Hungary's opening of its border with Austria in a striking move away from Soviet control.