Which type of message can be sent using DSC technology?

The correct choice is the ability to send preset distress messages using DSC (Digital Selective Calling) technology. DSC is a significant advancement in maritime communication, specifically designed for distress and safety applications. It allows vessels to send alerts that can quickly notify nearby ships and coast stations about emergencies.

When a vessel sends a DSC distress message, it typically includes vital information such as the vessel's identity, its position, and the nature of the distress. This type of message is particularly important during emergencies as it is transmitted automatically and can be received by multiple vessels simultaneously, enhancing the chances of a timely response.

The other options do not accurately represent the capabilities of DSC technology. Real-time video transmission is not supported, as DSC focuses primarily on digital signals rather than multimedia transmission. Written text messages are also not part of its functionalities, because DSC is built for structured distress messages rather than general text communication. Audio communication is traditionally handled by other radio systems rather than through DSC. Thus, the emphasis on preset distress messages showcases the essential role of DSC in enhancing maritime safety and operational efficiency.