This is a trick question. Actually all of the given choices are deployed as physical security access control.>>Edited for clarification, CCTV is a "preventive access control" according to ISC2 CISSP Study Guide 7th ed p. 75. According to the CISSP Study Guide 3rd ed. p. 185, "CCTV is a detective device used to aid guards in detecting the presence of intruders in restricted areas". CCTV is a detective controls, actual Security Cameras would be a preventative measure. |@Ajay: From Sybex Offical Study Guide pg 412. CCTV is a security mechanism related to motion detectors, sensors, and alarms. However, CCTV is not an automated detection-and-response system. CCTV requires personnel to watch the captured video to detect suspicious and malicious activities and to trigger alarms. Security cameras can expand the effective visible range of a security guard, therefore increasing the scope of the oversight. In many cases, CCTV is not used as a primary detection tool because of the high cost of paying a person to sit and watch the video screens. Instead, it is used as a secondary or follow-up mechanism that is reviewed after a trigger from an automated system occurs. In fact, the same logic used for auditing and audit trails is used for CCTV and recorded events. A CCTV is a preventive measure, whereas reviewing recorded events is a detective measure.