The IT department at a governmental agency is actively responsible for ensuring the security of the agency's sensitive information and physical assets. Recently, concerns have arisen about unauthorized access to certain restricted areas within the building. To address this issue, the IT team is implementing access control measures to enhance physical security. The main objective is to restrict entry to authorized personnel only and prevent unauthorized individuals from gaining access to sensitive areas. What access control measures could the IT department implement in the office building to enhance physical security and prevent unauthorized access to restricted areas?

a) Biometric access control
b) Keycard access control
c) Security guards
d) Surveillance cameras