Final answer:
A conventional fire alarm system requires firefighters to search the entire building to find the activated initiation device, leading to uncertainty regarding the presence of a serious fire or hazard and potential extreme physical danger.
Step-by-step explanation:
The fire alarm system that requires firefighters to search the entire building to locate the activated initiation device is known as a conventional fire alarm system. In these systems, there's uncertainty over whether a serious fire or hazard awaits after an alarm is triggered. This is because the alarm system indicates the general zone of activation but does not specify the exact location of the triggered device. This creates a potential for extreme physical danger as firefighters may have to systematically search the area until they find the source of the alarm, all while not knowing the severity or scale of the hazard they're dealing with.