What physical security measure is best to prevent unauthorized entry?

Mantraps are highly effective physical security measures designed to prevent unauthorized entry by controlling access to secure areas. They consist of a small room or compartment that requires individuals to authenticate themselves before passing through a second door. This two-door system ensures that only one person can enter the secure area at a time and can effectively prevent tailgating or unauthorized individuals from entering behind an authorized person.

In higher-security environments, mantraps can also include additional features such as biometric scanners, card readers, or cameras, further enhancing security. By limiting access and allowing for verification of individuals before entry, mantraps create a strong physical barrier against unauthorized personnel, making them an ideal measure for protecting sensitive areas.

The other options, while contributing to security, do not provide the same level of direct control over access as mantraps. Alarms can alert personnel to unauthorized access but do not physically prevent entry. Signage may inform individuals of restricted areas but lacks any enforcement capabilities. Lighting can deter criminal activity through increased visibility but does not provide a physical barrier to entry.