Where is the LDAP administrator account defined?

After analyzing a slapd.conf file, an administrator noted that the rootdn and rootpw directives are not present. Where is the LDAP administrator account defined?

A.
The account is defined in the file /etc/ldap/secret

B.
It is using the default account admin with the password admin ActualTests.com

C.
The account is defined by an ACL in slapd.conf

D.
It is using the default account admin with a null password

E.
The account is defined in the file /etc/ldap.root.conf