Why is the Supremacy Clause considered to be “the root of federalism”?

The Supremacy Clause establishes that the U.S. Constitution and federal laws made under it take precedence over conflicting state laws. This defines how federal and state authority relate to one another, which is why it is considered “the root of federalism.” Choice A describes that relationship; the clause does not list individual rights or state-reserved powers, and it does not make the president the supreme law.

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