Our federal system of government is based on which idea described below?

A) The national government has all the important powers to make all decisions; state governments are powerless.
B) State governments have all the power, and the national government can only do what the states allow them to do.
C) National and state governments operate under a system of shared power and responsibilities.
D) Local governments possess all the power and make all the day-to-day decisions about government.