What are the advantages of using LDAP over AD is true?

What are the advantages of using LDAP over AD is true?
A . LDAP allows for granular policy control, whereas Ad does not
B . LDAP provides for faster authentication
C . LDAP can be configured to use primary and secondary server, whereas AD cannot
D . LDAP does not require ISE to join the ad domain
E . The closest LDAP servers are used for Authentication

Answer: C