The President Issued an Executive Order Requiring That Every Citizen

The president issued an executive order requiring that every citizen purchase a head of broccoli to eat once a week in order to maintain health. The executive order was challenged and the case went to the U.S. Supreme Court. The Supreme Court declared the executive order could not be enforced because it was an abuse of the president's power. What is the primary source of law the Supreme Court would interpret to determine if the executive order was enforceable?

A) The Constitution
B) State statutes
C) Case law
D) Uniform laws
E) Executive orders