Answer is C. Government agencies and civilians.
In the U.S, only the president can emit a directive called executive order, which directs operations of the federal government and has the power of law.
Executive orders, as well as legislative statutes and regulations declared by government agencies, must be reviewed by the judicial power and may be rejected if unconstitutional. Also, these orders have major power over internal concerns of the government, determining the manner and degree of legislation enforcement, taking care of emergencies, waging wars, and more.