Which of the following statements concerning maintenance requirements is true?

Correct Answer: Option A — The options are duplication of equipment, at-sea maintenance, and shore-based maintenance.

GMDSS maintenance requirements under SOLAS Chapter IV, Regulation 15, explicitly define the three accepted methods: duplication of equipment, at-sea maintenance, and shore-based maintenance. Vessels must utilize these options based on their operational sea area to ensure the availability of radio equipment for distress and safety communications at all times.