Which of the following is an example of a physical security control?

Physical security controls are measures designed to protect the physical assets of an organization from unauthorized access, damage, or interference. Access control systems are a prime example of this type of control as they involve mechanisms like security gates, card readers, biometric scanners, and locks that restrict who can enter a physical location. These systems help ensure that only authorized personnel can gain access to sensitive areas, thereby safeguarding important assets.

This contrasts with the other options listed. Data encryption protects information in a digital format but does not provide a physical barrier to access. User authentication, while crucial for validating user identities within systems, mainly addresses digital access rather than the protection of physical spaces. Application firewalls serve to protect data and applications on networks, focusing on cybersecurity rather than physical asset security. Therefore, access control systems stand out as the correct example of a physical security control.