What is the default DN of the container where users and groups are stored?

When configuring a UNIX client to r, the top-level entry in the domain is dc=ad,dc=example,dc=com .
What is the default DN of the container where users and groups are stored?

A.
CN=USERS,DC=AD,DC=EXAMPLE,Dc=COM

B.
CN=PUBLIC,DC=AD,DC=EXAMPLE,Dc=COM

C.
CN=USERS,DC=AD,DC=EXAMPLE,Dc=ORG