What safety item is required for signaling distress at sea?

The requirement of a flare as a safety item for signaling distress at sea is grounded in its effectiveness and visibility. Flares are specifically designed to be used in emergency situations and can be seen from a significant distance, especially at night or in poor visibility. They produce bright, intense light and can be colored to attract attention—red being commonly used for distress signals. This makes them a recognized means of signaling for help, as they meet international maritime safety regulations.

In contrast, while a whistle and sound signal can be useful for communication over short distances, they do not have the same level of visibility and recognition as flares when it comes to signaling distress. A life jacket, although essential for safety and personal flotation, does not serve the function of alerting others to a distress situation. Thus, the flare's specific design and purpose make it the recommended choice for signaling distress at sea.