How were state constitutions important to the writing of the U.S. Constitution?

A.
Most states had learned that having a strong central government was a mistake.

B.
Small and large states came to the Constitutional Convention agreeing on how to set up a congress.

C.
Lessons learned in setting up state governments were helpful in setting up the United States government.

D.
None of the state constitutions contained guarantees of personal rights and freedoms.