What safety equipment is mandatory on commercial aircraft?

The choice highlighting emergency exit signs, fire extinguishers, and oxygen masks represents critical safety equipment that is mandated on commercial aircraft. Emergency exit signs are vital for guiding passengers towards exits in low-visibility situations or during evacuations; they ensure that individuals can quickly locate exits in an emergency scenario. Fire extinguishers are crucial for tackling onboard fires, which can arise unexpectedly during flight, while oxygen masks are essential for providing supplemental oxygen to passengers and crew in the event of cabin depressurization, a scenario that can occur during emergencies, such as rapid altitude changes or structural failures.

Safety measures like these are foundational to aviation regulations, designed to protect passengers and crew in various emergency situations. Other options, while they may include useful equipment, do not encompass the mandated items required for commercial aircraft operations as stipulated by aviation safety regulations.