Under the Supremacy Clause of the U

Under the Supremacy Clause of the U.S.Constitution,when Congress chooses to regulate in an area:

A) it will automatically have exclusive jurisdiction to regulate in that area.
B) states will always remain able to freely regulate in that area.
C) states will always be able to regulate in that area, so long as the state law does not directly and substantially conflict with the federal law.
D) whether the state has any authority to regulate in the area will depend on whether Congress provides that the federal government has exclusive authority to regulate in that area.
E) the state will be able to regulate in that area only with prior permission of the U.S. Supreme Court.