The correct answer is D) All of the above. The Global Maritime Distress and Safety System (GMDSS) has specific equipment carriage requirements, personnel requirements, and procedures for distress alerting and response. Vessels operating in GMDSS-applicable areas must carry the required GMDSS equipment, and must have at least two licensed GMDSS radio operators on board to properly operate the equipment and respond to distress calls. The comprehensive GMDSS requirements, including equipment, personnel, and distress procedures, make D) the correct answer.