What is the purpose of enabling Windows Active Directory Domain Authentication on FortiAuthenticator?

According to the FortiAuthenticator Administration Guide2, “Windows Active Directory domain authentication enables FortiAuthenticator to join a Windows Active Directory domain as a machine entity and proxy authentication requests using Kerberos.” Therefore, option D is true because it describes the purpose of enabling Windows Active Directory domain authentication on FortiAuthenticator. Option A is false because FortiAuthenticator does not need Windows administrator credentials to perform an LDAP lookup for a user search. Option B is false because FortiAuthenticator does not use a Windows CA certificate when authenticating RADIUS users, but rather its own CA certificate. Option C is false because FortiAuthenticator does not import users from Windows AD, but rather synchronizes them using LDAP or FSSO.