SECNAV M-5216.5 along with which other series are the two primary sources for the proper preparation of correspondence?

The correct choice for the two primary sources for the proper preparation of correspondence alongside SECNAV M-5216.5 is the instruction outlined in OPNAVINST 5215.17. This instruction provides additional guidelines that complement SECNAV M-5216.5, which governs the procedures for writing and processing official correspondence, ensuring that the correspondence adheres to the required format, tone, and protocol.

These two sources together establish a comprehensive framework for effective communication within the Navy and Marine Corps, tailoring the correspondence process to meet the unique needs and standards of each service. This combination is essential for maintaining consistency, clarity, and professionalism in communications.

Other options do not serve as primary sources for correspondence preparation. NAVFAC P-307, for instance, pertains more to project management and construction, while COMNAVSURFORINST 3100.4 and MCO 5216.2 address different aspects of naval and Marine Corps operations, respectively. Thus, they do not focus directly on correspondence preparation as strongly as OPNAVINST 5215.17 does.