Comprehensive and Detailed Step-by-Step Explanation:
Fire Alarm System Initiation:
Fire alarm systems can be initiated through multiple methods as per NFPA 72 (National Fire Alarm and Signaling Code), Chapter 17:
Manual Fire Alarm (I): Initiated by individuals using manual pull stations.
Automatic Detector (II): Initiated by devices like smoke detectors, heat detectors, or flame detectors.
Extinguishing System (III): Automatic suppression systems (e.g., sprinklers) can activate the fire alarm when they discharge.
Why All Three Are Valid:
Manual alarms allow for immediate activation.
Automatic detectors provide early warning.
Extinguishing systems ensure fire alarm activation during suppression.
Other Options Explained:
Option A (I and II): Excludes extinguishing systems, which can also initiate alarms.
Option B (I and III): Excludes automatic detectors, a common initiation method.
Option D (II and III): Excludes manual fire alarms.
Summary:
All three-manual fire alarms, automatic detectors, and extinguishing systems-can initiate a fire alarm system. The correct answer is I, II, and III .