Correct Answer: D
Explanation/Reference:
http://technet.microsoft.com/en-us/library/cc756901%28v=ws.10%29.aspx
Active Directory Logical Structure Background Information
Before you design your Active Directory logical structure, it is important to understand the Active Directory logical model. Active Directory is a distributed database that stores and manages information about network resources, as well as application-specific data from directory enabled applications. Active Directory allows administrators to organize elements of a network (such as users, computers, devices, and so on) into a hierarchical containment structure. The top-level container is the forest. Within forests are domains, and within domains are organizational units. This is called the logical model because it is independent of the physical aspects of the deployment, such as the number of domain controllers required within each domain and network topology.
Figure 2.2 Relationship Between Active Directory Forests, Domains, and OUs
