Which FortiSIEM feature must you use to produce a report on which FortiGate devices in...

 Feature Overview: FortiSIEM provides several tools for querying and reporting on device information within an environment.

 Inventory Tab: The Inventory tab is specifically designed to display detailed information about devices, including their firmware versions.

 Query Functionality: Within the Inventory tab, you can run queries to filter and display devices based on specific attributes, such as the firmware version for FortiGate devices.

 Report Generation: By running a query in the Inventory tab, you can produce a report that lists the FortiGate devices and their corresponding firmware versions.

 References: FortiSIEM 6.3 User Guide, Inventory Management section, explains how to use the Inventory tab to query and report on device attributes.