An engineer needs to permit XML API access to a firewall for automation on a...

To enable XML API access to a firewall for automation from a network segment routed through a Layer 3 sub-interface, the most straightforward approach is to use an Interface Management profile.

C. This can be achieved by:

Configuring an Interface Management profile and enabling HTTPS access on it. This profile defines management services that are permitted on the interface, including HTTPS, which is required for XML API access.

Applying this Interface Management profile to the desired Layer 3 sub-interface. This action enables HTTPS access (and thus XML API access) on the sub-interface, allowing devices on the connected network segment to communicate with the firewall for automation purposes.

This solution allows for the secure extension of management capabilities to network segments without direct access to the dedicated management interface, facilitating automation and operational efficiency without necessitating changes to existing access configurations.