Which of the following are the layers of physical security? Each correct answer represents a complete solution. Choose all that apply.

A.
Intrusion detection system

B.
Procedural access control

C.
Environmental design

D.
Video monitor

Explanation:
Environmental design is the initial layer of security for a campus, building, office, or physical space. It is used to determine threats. Some of the most common examples are also the most basic – barbed wire, warning signs and fencing, concrete bollards, metal barriers, vehicle height-restrictors, site lighting, and trenches.
Procedural access control includes the use of policies, processes, and procedures to manage the ingress into the restricted area. An example of this is the deployment of security personnel conducting checks for authorized entry at predetermined points of entry. It is the second layer of physical security.
The third layer is the intrusion detection system. It is a device (or application) that monitors network and/or system activities for malicious activities or policy violations and produces reports to a Management Station. Intrusion detection is the process of monitoring the events occurring in a computer system or network and analyzing them for signs of possible incidents, which are violations or imminent threats of violation of computer security policies, acceptable use policies, or standard security practices.A video monitor, also called a broadcast monitor, broadcast reference monitor, or just reference monitor, is a device similar to a television, used to monitor the output of a video- generating device, such as a media playout server, IRD, video camera, VCR, or DVD player. Video monitors are used extensively in the security industry with closed-circuit television cameras and recording devices. It is the last layer of physical security.