Which of the following is a preventive physical security control?

Video surveillance systems are primarily used for monitoring and recording activities within a designated area. While they play a critical role in security by providing evidence and deterring potential threats, they do not physically prevent unauthorized access, thereby categorizing them as detective controls rather than preventive.

Alarm systems are designed to alert personnel of unauthorized access or breaches when they occur. Similar to video surveillance, alarms serve a reactive purpose, notifying security teams of incidents but not physically obstructing threats before they happen.

Motion sensors detect movement within a specified area and trigger alerts or responses when movement is detected. Although they can enhance security by providing real-time alerts, they do not physically block or prevent access, placing them in the category of detection rather than prevention.