Answer:
The Constitution gives only Congress the power to make rules for governing the armed forces.
Step-by-step explanation:
Section 8, Article II of the U.S. Constitution explicitly gives Congress a series of powers toward the military branches of the U.S., including the power to raise and support federal armies, to create and maintain a navy, to make rules for the regulation of the land and naval forces, and to organize, arm discipline and govern the militia.
Furthermore, the section also provides that Congress can make all laws "necessary and proper" for carrying into execution those powers, and this includes to make rules governing the armed forces.