What distinguishes an emergency signal from a normal alarm?

An emergency signal is designed to convey immediate and critical information about serious situations that necessitate prompt action from crew members. This signal often indicates life-threatening scenarios, such as a fire, flooding, or man overboard, where quick and decisive responses are essential for safety.

In contrast, other options do not accurately depict the distinction. While it is true that some normal alarms can be false, they are not categorically always false, as some may indicate non-critical issues that still require a response but are not life-threatening. Additionally, emergency signals are not limited to specific drills; they apply during actual emergencies. Lastly, normal alarms, while they may sometimes indicate situations that do not require an emergency response, can still necessitate action depending on the nature of the alert. Therefore, the key difference highlighted in the correct choice emphasizes the severity and urgency of emergencies, which is critical for preparedness and safety on board.