Which of the following is a functional or carriage requirement for compulsory vessels?

Correct Answer: Option D — All of the above

Compulsory vessels under SOLAS Chapter IV must adhere to strict GMDSS standards. This includes maintaining qualified personnel, carrying equipment specific to the vessel's operational sea area, and ensuring the capability to transmit and receive distress alerts. These requirements ensure a standardized, reliable global maritime safety and distress response system.