Which of the following is a type of distress signal?

A red flare is a universally recognized distress signal used in maritime situations to indicate an emergency. When deployed, it produces a bright red light visible from a considerable distance, alerting nearby vessels and rescuers to the presence of someone in distress. Flares are specifically designed for signaling, and their color and brightness ensure they catch attention quickly, especially in situations where visibility might be limited.

In contrast, while a flashing ice light may be used for navigation or to indicate a presence, it is not a recognized emergency signal like a flare. A fog horn is typically used for navigation through foggy conditions rather than signaling distress. Dropping anchor is a standard maneuver for maintaining position but does not convey an emergency situation. Thus, the red flare stands out as the clear choice for a distress signal in maritime contexts.