You are responsible for security at a building that has a lot of traffic. There are even a significant
number of non-employees coming in and out of the building. You are concerned about being able
to find out who is in the building at a particular time. What is the simplest way to accomplish this?

A.
Implement a sign in sheet at the main entrance and route all traffic through there.

B.
Have all people entering the building use smart cards for access.

C.
Implement biometric access.

D.
Implement cameras at all entrances.