What item must be displayed on vehicles in restricted areas?

In restricted areas of an airport, it is crucial for vehicles to display an airport-issued placard or identification. This requirement serves multiple purposes, primarily ensuring the security and safety of the airport environment. A placard or form of identification indicates that the vehicle is authorized to be in a sensitive area, helping to distinguish between those with legitimate access and unauthorized personnel.

The presence of this identification aids in maintaining security protocols, enabling airport personnel to quickly identify vehicles that are permitted and ensuring compliance with regulations specific to restricted zones. Such measures are vital to protecting both the airport infrastructure and the general public.

In contrast, the other options such as a parking permit, temporary visitor pass, or validation sticker do not necessarily denote authorization for restricted area access. While these items may be relevant for parking or temporary access under certain circumstances, they do not fulfill the critical function of identifying vehicles that are allowed to operate within restricted zones of the airport.