A datacenter audit finds that a number of personnel are not using access cards when entering a secured area with a coworker. Which of the following security methods could be implemented to help…

A mantrap is a physical security vestibule with two interlocking doors where only one door can be open at a time, requiring each individual to authenticate separately before the inner door unlocks. This design directly eliminates tailgating because an unauthorized person cannot slip through behind an authorized user - the first door must fully close and the individual must present valid credentials before the second door will open.

A keypad controls door access but does not physically prevent an unauthorized person from following an authenticated user through the same door before it closes.

A smart card reader similarly cannot stop someone from physically tailgating through the door immediately after an authorized user swipes their card.

Security cameras are a detective control that can record tailgating after the fact but do not physically prevent unauthorized personnel from entering.