Which one of the following is true regarding structural barriers?
A . Structural barriers serve as psychological deterrents.
B . The objective of barriers is to cause as much delay as possible.
C . A series of barriers are usually used in any effective physical protection plan.
D . A series of concentric barriers should separate the area to be protected.
E . Even with good planning, most structural barriers do not prevent penetration by humans.
F . All of the above.
Answer: F