In the event of engine failure or dual generator failure, what will the batteries provide power for?

The correct choice indicates that in the event of engine failure or dual generator failure, the batteries are designed to provide power for a maximum range glide and one attempted engine restart. This is an important safety feature in aviation, as it allows the crew to attempt to restore engine power while also managing a controlled descent.

During an engine failure scenario, the priority is to maintain control of the aircraft and to maximize the distance it can glide, which is critical for reaching a suitable landing area, such as an airport or a suitable terrain for a safe landing. The ability to attempt a restart is also vital, as there may be a chance to regain power and avoid a forced landing.

The other options do not fully encompass the capabilities expected from the aircraft's battery in such emergency scenarios. For instance, while emergency lighting is essential for safety, the primary function of the batteries during engine failure is to support vital systems for gliding and engine restart attempts. Similarly, providing power for cabin systems may not be a priority during such an emergency, as the focus will be on flight control and safety measures rather than maintaining passenger comfort or cabin operations. Additionally, continued flight until reaching the nearest airport implies sustained power which might not be feasible with just battery backup in that situation.