What must be done to allow only users of the devel system group to access a share?

What must be done to allow only users of the devel system group to access a share?

A.
In the smb.conf file, set valid groups=@devel

B.
In the smb.conf file, set valid users=@devel

C.
In the smb.conf file, set valid groups=devel

D.
Chgrp the directory on the samba server to the devel group and then set the GID bit on the
directory