A technician was dispatched to complete repairs on a server in a data center. While locating the server, the technician entered a restricted area without author...

A technician was dispatched to complete repairs on a server in a data center. While locating the server, the technician entered a restricted area without authorization. Which of the following security controls would BEST prevent this in the future?

A. Use appropriate signage to mark all areas. B. Utilize cameras monitored by guards. C. Implement access control vestibules. D. Enforce escorts to monitor all visitors.