Which publication serves as the official naval guide for the preparation of correspondence?

The correct answer is SECNAVINST 5216.5, which serves as the official reference for preparing correspondence within the Navy and Marine Corps. This instruction provides comprehensive guidelines on the format, standards, and procedures for official correspondence to ensure consistency and professionalism across all communications. It outlines elements such as addressing, signature blocks, and the use of appropriate language in correspondence, which are fundamental for clear and effective communication in military contexts.

In contrast, the other publications listed may have relevance in other areas but do not specifically serve as the official guide for correspondence preparation. NAVEXOS P-35 relates to visual signals and other forms of communication but does not address correspondence directly. DoD Manual 5000.01 focuses on defense acquisition, while COMNAVFORCOMINST 5216.1 pertains to specific operational instructions within certain commands, rather than the standardized preparation of correspondence. Thus, SECNAVINST 5216.5 is uniquely dedicated to this purpose, making it the correct choice.