Which category is considered the least severe for runway incursions?

The correct choice indicates that Category D incursions are considered the least severe type of runway incursion. This classification reflects an event where an aircraft, vehicle, or person incurs onto a runway but does not compromise safety. Specifically, Category D typically involves situations that do not cause a significant risk of collision or incident.

For instance, examples of Category D incursions may include minor unauthorized entries onto the runway that do not interfere with ongoing operations or the movement of aircraft. Such events may be the result of a misunderstanding or momentary lapse in communication rather than a direct threat.

The classifications increase in severity with Categories A, B, and C, which encompass situations ranging from significant potential for an accident to an actual collision. Understanding these categories helps drivers on the airport's AOA (Air Operations Area) maintain situational awareness and prioritize safety during their operations.