What emergency equipment is required on board all commercial aircraft?

The requirement for emergency equipment on all commercial aircraft is critical to ensure passenger safety and compliance with aviation regulations. The correct answer identifies that a fire extinguisher, first-aid kit, and survival gear for over-water cross-country flights are essential components of the safety equipment on board.

Fire extinguishers are vital for addressing potential onboard fire incidents, as they can prevent small fires from escalating. A first-aid kit is necessary to provide basic medical assistance for any injuries that may occur during the flight. Survival gear, particularly for over-water flights, is required to ensure the crew and passengers can survive should an emergency landing in water occur. This gear typically includes life vests, personal flotation devices, and items that may aid in survival, such as signaling devices.

Other answer choices do not encompass the entire range of required emergency equipment universally mandated for commercial aviation. While they mention important safety items, they lack the comprehensive list that includes all the mandatory gear needed for varied flight operations, especially those that have the potential for over-water emergencies. Thus, option B represents the most thorough understanding of what is required on commercial aircraft to guarantee passenger safety in emergencies.