Which of the Following Statements About the Federal System Adopted

Which of the following statements about the federal system adopted at the Constitutional Convention is most accurate?

A) It had been tried without success in other countries.
B) It was adopted as an alternative to a confederate system, in which local governments are granted a specially protected existence.
C) It granted supreme authority to neither national nor state government.
D) It specifically reserved powers not delegated to the United States by the U.S. Constitution to the states.
E) It guaranteed the dominance of the states for several hundred years.