C . One or more remote LDAP servers: FortiAnalyzer needs to be configured to communicate with your external LDAP server where the user accounts and groups reside. This involves setting up the LDAP server address, port, and authentication details.
B . An administrator group: You need to create an administrator group on FortiAnalyzer and link it to the specific LDAP group that contains the users you want to grant administrative access. This allows any user within that LDAP group to authenticate and have the permissions assigned to the administrator group on FortiAnalyzer.
This configuration allows FortiAnalyzer to authenticate users against the external LDAP server and authorize them based on their membership in the designated LDAP group. This way, you don't need to create individual local accounts for each administrator, simplifying user management and centralizing authentication.

https://kb.fortinet.com/kb/documentLink.do?externalID=FD40383