Final answer:
An exit-control alarm, a security device used to monitor individual passages at exits, would most likely be found in an airport.
Step-by-step explanation:
Exit-control alarms are security devices used to monitor and control the passage of individuals through exits. They are particularly common in high-security areas where ensuring individuals do not carry prohibited items out of, or into, a secure zone is crucial.
In the context of an airport, such an alarm system may not only detect metals but can also provide an indication of their approximate height above the floor. This is essential for security personnel to quickly identify and respond to potential threats or contraband. The presence of an exit-control alarm system at airports helps to manage the uncertainty over whether a serious fire or hazard awaits after an alarm is activated, and it addresses the potential for extreme physical danger associated with unauthorized access or the smuggling of dangerous items.
Therefore, when considering where an exit-control alarm would most likely be found, an airport serves as a prominent example of a building type that utilizes this kind of security measure extensively.