The supremacy clause is a provision of the United States Constitution that A) grants Congress the power to regulate trade with foreign nations, and among the several states, and with the Indian tribes B) mandates that each state respect and enforce both the judgments awarded by courts in other states, and the statutes and case law of other states C) requires state judges to follow federal law in the event of a conflict with state law D) prohibits the states from discriminating on the basis of race or national origin