Which of the following describes a turnstile?

A turnstile serves as a physical barrier that allows only one person to enter at a time, ensuring controlled access to a specific point. Typically found in locations such as public transit stations, amusement parks, and secure buildings, turnstiles enhance security by preventing unauthorized access and managing the flow of individuals through a designated entry point. These devices require users to engage with the turnstile, often by inserting a ticket or swiping an access card, thus permitting only one individual passage through the barrier with each interaction. This design is effective in maintaining order and security in environments where monitoring the number of entries is crucial.