What must a firefighter use to report an emergency situation on the fire ground?

When a firefighter encounters an emergency situation on the fire ground, utilizing a MAY-DAY call is essential for several reasons. Specifically, a MAY-DAY call is a standardized and recognized alert that indicates a firefighter is in distress or requires assistance. This alert is crucial as it not only communicates the urgency of the situation but also triggers a specific response protocol among crew members, enhancing the chances of a timely rescue.

The MAY-DAY call conveys critical information quickly and efficiently to other firefighters and incident command, allowing them to assess the situation and act accordingly. This terminology is widely understood in the fire service, and using it fosters quick recognition of the need for immediate support.

The other options, while relevant to communication on the fire ground, may not specifically indicate an emergency situation unique to a firefighter's distress. Radio communication is essential for regular updates and commands, a distress signal might not be universally understood, and an emergency alarm system could alert the broader team but may not provide the immediate context necessary for a rescue. Thus, the specificity and urgency embedded in a MAY-DAY call make it the appropriate choice for reporting emergencies.