Which ancient civilization developed the first democratic form of government?

When the framers our state's constitution began to create it, they looked to the u.s. constitution as a model. much like the national government, they created a state government in which each branch could keep the others from having too much power. for example, the state supreme court can- once a law has been passed and enforced- rule that the law violates the state constitution. if this happens, the law is no longer enforced. what principle of government is being described in this passage? a) federalism b) separation of powers c) checks and balances d) republican government