Which of the following is absolutely prohibited in a passenger cabin during a flight?

Gas and butane lighters are strictly prohibited in the passenger cabin during a flight due to safety concerns. These items are classified as hazardous materials because they can easily ignite and pose a significant fire risk within the confined space of an aircraft. The potential for an uncontrolled fire in an environment with flammable materials increases the danger to passengers and crew.

While non-alcoholic beverages are allowed, portable oxygen concentrators can be used under specific guidelines, and emergency oxygen masks are essential safety equipment provided for passenger and crew use in case of cabin depressurization, their presence is crucial for safety and is not prohibited. Therefore, gas and butane lighters are the item that is unequivocally banned to ensure the safety and security of everyone onboard.