The correct answer is: "Jean Jacques Rousseau".
The Enlightenment philosophers, such as Locke, Monstequieu or Rosseau, introduced principles that challenged, and ended up derrocating the predominant power structures of the Old Regime. They promoted reason and the scientific method as the alternative to religious dogmatism and superstititions.
Jean-Jacques Rousseau introduced the concept of social contract. It established that citizens were the ones who held power legitimately, and these should grant it to representatives elected through suffrage, that would conform the goverments. This viewpoint sharply contrasted with the absolute monarchies that ruled in most European countries.
