Which of the following is the MOST effective at preventing an unauthorized individual from following an authorized person through a secured entrance (tailgating or piggybacking)?

A.
Card-key door locks

B.
Photo identification

C.
Biometric scanners

D.
Awareness training

Explanation:
Awareness training would most likely result in any attempted tailgating being challenged by the authorized employee. The other choices are physical controls which by themselves would not be effective against tailgating.