Which type of distress signal indicates an emergency situation requiring immediate assistance?

A distress signal that indicates an emergency situation requiring immediate assistance is "Mayday." This term is part of the international radiotelephony distress signal and is recognized universally as a call for urgent help. When a person or vessel transmits "Mayday," it conveys a situation in which the safety of the vessel or individual is threatened, and immediate rescue is necessary.

The use of "Mayday" specifically indicates that lives are at risk, which is crucial in prioritizing responses during emergencies. This calls for the highest level of urgency from rescue services. Understanding the distinction between various distress signals, such as "SOS," which is a general call for help, and "Pan-pan," which indicates a situation that is urgent but not life-threatening, clarifies why "Mayday" is the correct choice in situations demanding immediate assistance.