Which user group types does FortiGate support for firewall authentication? (Choose three.)

RSSO (RADIUS Single Sign-On) is a supported user group type that allows FortiGate to authenticate users through a RADIUS server, often leveraging existing enterprise user directories for single sign-on capabilities.

Firewall user groups are locally defined on the FortiGate device, allowing administrators to create and manage user accounts and groups directly on the firewall for authentication and policy enforcement.

LDAP (Lightweight Directory Access Protocol) is an authentication *protocol* used by FortiGate to communicate with directory servers, but it is not a 'user group type' itself; rather, FortiGate uses it to query groups from an external server.

NTLM (NT LAN Manager) is an authentication *protocol*, not a user group type. While FortiGate can use NTLM for authentication, it refers to the protocol for challenge-response authentication, not a group category.

FSSO (Fortinet Single Sign-On) is a supported user group type that integrates with Microsoft Active Directory to provide transparent authentication for users based on their Windows logon events.