Explanation: For GMDSS vessels operating internationally under FCC jurisdiction, adherence to specific regulations and publications is paramount. Answer D is correct because: * **Part 80 FCC rules** govern maritime radio services in the U.S., including GMDSS. All U.S.-flagged vessels must comply. * **Station logs** are required by both national and international regulations to record GMDSS communications, equipment tests, and incidents. * **Station licenses** (for the vessel itself) are mandatory for operating radio equipment. * **ITU publications** (International Telecommunication Union) define international radio regulations, frequencies, and operational procedures essential for GMDSS. * The **ITU Manual for Maritime Mobile stations** (officially "Manual for Use by the Maritime Mobile and Maritime Mobile-Satellite Services") is the definitive international publication detailing GMDSS procedures, distress calls, and general radiocommunication for maritime vessels. Option A is incorrect because the IMO Master Plan isn't a required onboard document, and Inmarsat is a system, not a publication. Option B lists navigational aids (NGA Pub. 117) and a SAR manual (IAMSAR), which are useful but not the core regulatory/procedural documents for GMDSS *operation*. Option C is very close but incorrectly states "IMO manual for Maritime Mobile stations" instead of the correct "ITU manual for Maritime Mobile stations." The ITU, not IMO, publishes the comprehensive manual for maritime radio communications.