Which of the following is the most common type of physical access control?

Locks and keys are the most fundamental form of physical access control, widely utilized across various security systems. They provide a straightforward method of restricting access to authorized individuals. By using a physical key or lock mechanism, organizations can effectively prevent unauthorized personnel from entering sensitive areas, safeguarding both physical assets and confidential information.

This method is recognized for its simplicity and effectiveness, making it a staple in security practices. While other options, such as employee identification cards, alarm codes, and special visitor passes, also serve as access controls, they often work in conjunction with locks and keys to enhance security. However, locks and keys are typically the primary line of defense and the first layer of security in many physical security systems.