Final answer:
The explosive growth phase of a compartmentalized fire is a significant threat in today's building fires.
Step-by-step explanation:
The explosive growth phase of a compartmentalized fire is a very real threat that is likely in today's building fires. This phase occurs when a fire transitions from a localized and contained state to a rapid and uncontrolled spread throughout the building. During this phase, there is uncertainty over whether a serious fire or hazard awaits after an alarm, and there is a potential for extreme physical danger.