Explanation: GMDSS regulations are designed to ensure maximum reliability of distress and safety communications, even in catastrophic situations. This necessitates robust and redundant power sources. **Why D is correct:** Newly constructed GMDSS ships must have both **emergency power** and **reserve power** sources for their radio communications equipment. * **Emergency power** typically refers to an alternative power supply (like a generator or separate bus) that can power essential systems, including GMDSS equipment, if the ship's main power fails. * **Reserve power** refers to dedicated batteries designed to provide power to critical GMDSS radio equipment (VHF, MF/HF, Inmarsat terminals) for a specified duration (e.g., 1 or 6 hours) in the event of a complete loss of main and emergency power. **Why A, B, and C are incorrect:** * **A) and B)** are incorrect because GMDSS explicitly requires *both* an emergency power source and a reserve power source (batteries). They serve different but complementary roles in ensuring power continuity for critical communications. One does not negate the need for the other. * **C)** is incorrect because the power requirements for fixed GMDSS radio installations are independent of the number of EPIRBs. While additional EPIRBs provide distress alerting redundancy, they do not alleviate the mandatory power requirements for the ship's main GMDSS communication equipment.