Final answer:
The Chief of Naval Operations is the principal adviser to the Secretary of the Navy, serving as the top uniformed military officer in the Navy.
Step-by-step explanation:
The principal adviser to the Secretary of the Navy is A) Chief of Naval Operations. This position is occupied by the top uniformed military officer in the Navy. In contrast, the Secretary of Defense is the civilian head of the entire Department of Defense, while the position of Fleet Admiral, once held by Admiral Chester Nimitz during and after World War II, represented the highest-ranking officer in the Navy at the time. Admiral Nimitz notably accepted the surrender of Japanese forces aboard the USS Missouri. The Chief of Naval Operations plays a key strategic role, providing expert advice on naval matters to the Secretary of the Navy, who is part of the executive departments the President may consult according to Section 2 of the Constitution.