Which of the following best describes the primary function of a FortiGate firewall?

The primary function of a FortiGate firewall is to implement and enforce security policies. This involves controlling access to the network by defining rules that determine what traffic is allowed or denied based on various criteria, such as IP address, application type, and user identity. By doing this, FortiGate firewalls protect the network from unauthorized access, mitigate potential security threats, and ensure compliance with organizational security standards.

Other options like data backup and recovery, monitoring application performance, and user authentication and access control, while important functions within IT security and network management, are not the primary focus of a firewall. Data backup and recovery are typically handled by dedicated backup solutions, application performance monitoring relies on different tools designed for that purpose, and user authentication and access control, while critical, are often integrated components rather than the core function of the firewall itself.