When may the operator of a ship radio station allow an unlicensed person to speak over the transmitter?

The correct answer is that an unlicensed person may speak over the transmitter when under the supervision of the licensed operator. This provision allows for the inclusion of unlicensed individuals in communication processes on board, which can be beneficial for training purposes or in situations where the licensed operator is momentarily preoccupied but still able to oversee operations.

The supervision requirement ensures that a knowledgeable and authorized person is present to maintain control over the radio equipment and to ensure compliance with FCC regulations. This enhances safety and operational standards, as the licensed operator can ensure that transmissions are made appropriately and legally, adhering to the rules governing maritime communications.

In contrast, the other options include strict rules that either ban unlicensed operators entirely or set conditions that do not align with FCC regulations. Banning unlicensed speech at all times may overlook circumstances where supervision is possible and deemed safe, while restrictions based on power output or duty hours do not apply in the context of supervision, which is the differentiating factor in the allowed scenarios for communication.