Which of the following is a preventive physical security control?

Bollards are a preventive physical security control because they are designed to physically block or deter unauthorized vehicle access to a protected area. They are a proactive measure to prevent an incident from occurring. Video surveillance systems are a detective control, as they record events for later review but do not prevent an incident in real-time. Alarm systems are also detective controls, alerting personnel after an intrusion has been detected. Motion sensors are a type of detective control used within an alarm system to detect movement, triggering an alert rather than preventing entry.