What does the lavatory fire detection system utilize to trigger halon discharge?

The correct choice emphasizes the specific technology employed in lavatory fire detection systems, which is critical for ensuring passenger safety and effective response to potential fire threats.

In fire detection systems, the combination of a smoke detector and heat-sensitive capsules serves as an effective method for identifying the presence of fire. The smoke detector continuously monitors for smoke particles, which are indicative of combustion. Simultaneously, the heat-sensitive capsules respond to elevated temperatures associated with a fire. When either of these components detects the signs of a fire—whether through smoke or excessive heat—it activates the release of halon, a fire suppression agent that is effective in extinguishing fires without leaving residue that could damage aircraft systems.

Other choices do not detail the right combination of technologies used for activating the halon discharge. The use of a manual trigger, for instance, would not allow for the rapid response needed in a lavatory environment, where fires can escalate quickly. Thus, the integration of both smoke detection and heat sensitivity offers a reliable automatic response to fire, ensuring timely actions to protect passengers and crew.