What are the two main types of distress signals used at sea?

The correct choice highlights the two main types of distress signals utilized at sea: visual signals, such as flares, and electronic signals, including Emergency Position Indicating Radio Beacons (EPIRBs).

Visual signals are crucial for alerting nearby vessels or aircraft to a distress situation, as these signals can be seen from a distance. Flares, for instance, produce bright flames or colored smoke that can attract attention even during daylight. On the other hand, electronic signals are vital for effective communication over longer distances or when visibility is compromised. EPIRBs automatically transmit distress signals that include the vessel's location, allowing rescue organizations to pinpoint the distress call's origin and respond accordingly.

This understanding of distress signaling is essential for safety at sea, as it ensures that mariners can effectively communicate their situation in emergencies, using both visible and electronic methods to maximize the chances of a timely rescue.