The correct answer is B. An appellate court.
Step-by-step explanation
The Supreme Court of the United States is the highest judicial court in that country. This entity is made up of a president and eight associate judges who are chosen by the president and subsequently validated by the Senate.
Among the functions of the Supreme Court are judicial review and the power to declare unconstitutional federal or state laws and acts of the federal and state executive powers. Likewise, decisions made by the Supreme Court cannot be appealed.
On many occasions, the Supreme Court has the function of being an appeals court because it resolves appeals made against decisions made in district courts and other cases of federal courts. Therefore, the correct answer is B. An appellate court.