What technology does GMDSS employ for distress signaling?

The correct choice is reflected in the use of advanced communication technologies within the Global Maritime Distress and Safety System (GMDSS). This system is primarily designed for vessel safety and distress signaling at sea, incorporating both satellite communication and digital selective calling (DSC) as its key components.

Digital selective calling allows a ship in distress to automatically alert the appropriate rescue services, providing critical information such as the vessel's identity and position. By leveraging satellites, GMDSS can ensure that distress signals are communicated over vast distances and are received even when vessels are beyond the range of traditional land-based radio stations. This combination of satellite technology and digital communication methods enhances the reliability and speed of distress signaling and improves the overall safety of maritime navigation.

Other technologies mentioned, such as radio waves, fiber optics, and ground-based systems, do not fully encompass the integrated approach that GMDSS offers. While radio is a traditional signaling method and may play a role in certain GMDSS functions, it does not capture the full capabilities of the system, particularly regarding automation and global reach. Fiber optics and ground-based systems also lack the necessary comprehensive global coverage and specificity required for effective maritime distress signaling.