What must airlines ensure about the passengers and their cabin baggage according to aviation security regulations?

Airlines are required to screen passengers and their cabin baggage before allowing them to board an aircraft to ensure the safety and security of everyone involved in the flight. The primary objective of this screening is to prevent prohibited articles from being brought onto an aircraft. Prohibited articles can include weapons, explosives, and other items that could pose a safety threat to the aircraft and its passengers.

This regulation is part of broader aviation security measures designed to mitigate risks associated with air travel, thereby protecting passengers, crew, and airport staff. The screening process involves the use of various technologies and methods, such as metal detectors and X-ray machines, to detect and identify items that should not be in a passenger's possession during a flight.

Focusing on the correct answer highlights the critical importance of proactive measures in aviation security to prevent potential threats rather than just assessing who can enter the terminal, checking passport validity, or requiring declarations of valuable items. These aspects, while important in their own rights, do not directly address the core concern of ensuring that no harmful items make it onto an aircraft.