Which instruction governs the correspondence within the Navy?

The instruction that governs correspondence within the Navy is SECNAVINST 5216.5C. This instruction outlines the policies and procedures for official correspondence within the Navy, ensuring that all written communication follows a standardized format. It sets guidelines for the preparation, formatting, and processing of various types of correspondence, including letters, memos, and directives. By adhering to this instruction, Navy personnel maintain professionalism and clarity in their communications, which is crucial for effective operations and information dissemination.

The other choices refer to different kinds of documents or instructions that do not specifically govern correspondence within the Navy. NAVSUP P-409 deals with supply procedures and policies, NAVSUP P-484 is focused on Navy logistics and supply operations, while NAVSO P-3013-2 pertains to Navy operational procedures. Each of these documents serves a vital role within their respective contexts but does not pertain to correspondence management as SECNAVINST 5216.5C does. This is why SECNAVINST 5216.5C is the correct choice for governing Navy correspondence.