Which User-ID mapping method should be used for an environment with clients that do not authenticate to Windows Active Directory?

Which User-ID mapping method should be used for an environment with clients that do not authenticate to Windows Active Directory?
A . Windows session monitoring via a domain controller
B . passive server monitoring using the Windows-based agent
C . Captive Portal
D . passive server monitoring using a PAN-OS integrated User-ID agent

Answer: C

Explanation:

https://docs.paloaltonetworks.com/pan-os/9-0/pan-os-admin/user-id/map-ip-addresses-to-users/map-ip-addresses-to-usernames-using-captive-portal.html