The final authority on legal questions in the United States is

the president.

the vice president.

the Senate.

the Supreme Court

D - the supreme court

It is the supreme court. Supreme court is the highest court within the hierarchy of courts in many legal jurisdictions. It is described as the court of the last resort, apex court, or the highest court of appeal. The decisions of the supreme court are not subject to further review by any other courts. In the US the supreme court is a federal court, meaning in part that it can hear cases prosecuted by the US government. The court may hear any kind of state-court case, as long as it involves federal law, including the constitution.