Which of the following physical controls provides the GREATEST assurance that only authorized individuals can...

 Access to the data center is controlled by a mantrap provides the greatest assurance that only authorized individuals can access a data center. A mantrap is a physical security device that consists of a small space with two sets of interlocking doors, such that the first set of doors must close before the second set opens1. A mantrap prevents unauthorized entry by requiring authentication at both doors, such as biometric scanners, card readers, or PIN codes. A mantrap also prevents tailgating, which is the act of following an authorized person into a restricted area without proper authorization2. A mantrap can also detect and trap intruders who attempt to force their way through the doors.

The other options are less effective physical controls for data center access. The data center is patrolled by a security guard is a deterrent measure, but it does not prevent unauthorized access by itself. A security guard may not be able to monitor all entry points, or may be distracted, bribed, or overpowered by intruders. Access to the data center is monitored by video cameras is a detective measure, but it does not prevent unauthorized access either. Video cameras can record the activities of intruders, but they cannot stop them from entering or alert the security personnel in real time. ID badges must be displayed before access is granted is a preventive measure, but it relies on human verification, which can be prone to errors or manipulation. ID badges can also be lost, stolen, or forged by intruders.