any entity in the AD is treated as and objects like user,computer, printer etc all the network resources are objects and each having some attributes.
A container object is one that can other objects housed within it. These can be additional container objects or leaf objects.
Out of the choices User, Group, Computer, and Organizational Unity the answer would be: Organizational Unit (pg. 31)Objects can placed into containers - logical groupings of related objects. For...
it is the user because you can not expand it
Try http://www.macwindows.com/AD.html