Which of the following controls is MOST effective in providing reasonable assurance of physical access compliance to an unmanned server room controlled with biometric devices?

Explanation:

A review of access control lists is a detective control that will enable an information security manager to ensure that authorized persons are entering in compliance with corporate policy. Visitors accompanied by a guard will also provide assurance but may not be cost effective. A visitor registry is the next cost-effective control. A biometric coupled with a PIN will strengthen the access control; however, compliance assurance logs will still have to be reviewed.