What must be checked for operation during pre-flight inspections related to emergency exit lights?

The requirement that emergency exit lights must be operable manually from both the flightcrew station and the passenger compartment ensures that in the event of an emergency, the flight crew and passengers can activate these lights, providing essential guidance towards exits. This manual operation is crucial because there could be situations where the automatic systems may fail or be non-functional due to various reasons, such as electrical failure or smoke in the cabin. By ensuring that these lights can be activated manually, it enhances safety and preparedness during emergencies, allowing for effective navigation out of the aircraft.

Other options touch on related concepts, but they do not reflect the primary operational checks that ensure readiness and safety. For example, while automatic activation linked to cabin pressure systems may impact functionality, it does not address the immediate need for manual operability by personnel inside the aircraft. The same applies to the visibility aspects mentioned; while important, they do not encompass the critical operational functionality during a pre-flight inspection.