What key idea in the constitution creates a division of power between national and state givers

The correct answer is Federalism. Indeed, when the Founding Fathers gathered in Philadelphia to replace the Articles of Confederation with permanent solution, they were met with the opposition of Southern planters who were afraid they would abolish slavery and who wanted to preserve what they named State's Rights.

Federalist lawmakers responded by creating the Bill of Rights, of which the Tenth amendment explicitly states that all powers not explicitly delegated to the Federal government by the Constitution are reserved powers of the states.