Which of the following methods utilizes a canine unit in aviation security?

Utilizing a canine unit in aviation security is most commonly associated with explosive detection dogs. These specially trained dogs have an acute sense of smell, allowing them to detect various types of explosives and explosive materials that may be concealed in baggage, cargo, or on a person. Their use in aviation security enhances threat detection and increases the efficiency of screening processes, providing an additional layer of safety in airports.

In contrast, the other methods mentioned—like X-ray screening, hand searches, and visual inspections—rely primarily on technology or human capabilities without the unique advantages provided by canine units. While X-ray screening uses imaging technology to examine contents within luggage, and hand searches coupled with visual inspections rely on personnel to evaluate items, explosive detection dogs are specifically trained to identify the scent of explosives, which can often be more comprehensive and quicker than mechanical or manual searches alone.