Question

what is the primary purpose of the supremacy clause?
to outline why some powers must be implied rather than detailed
to explain why state and federal powers are always kept equal
to describe the relationship between federal and state powers
to declare to american citizens the us is the supreme ruler

Explanation:

The Supremacy Clause in the U.S. Constitution establishes that federal law is the supreme law of the land. It defines the relationship between federal and state powers, stating that in case of conflict, federal law prevails.

Answer:

to describe the relationship between federal and state powers