Your network contains a single Active Directory domain.
You need to create an Active Directory Domain Services snapshot.
What should you do?

A.
Use the Ldp tool.

B.
Use the NTDSUtil tool.

C.
Use the Wbadmin tool.

D.
From Windows Server Backup, perform a full backup.

Explanation:
http://technet.microsoft.com/en-us/library/cc753609.aspx
To create an AD DS or AD LDS snapshot
1. Log on to a domain controller as a member of the Enterprise Admins groups or the
Domain Admins group.
2. Click Start, right-click Command Prompt, and then click Run as administrator.
3. If the User Account Control dialog box appears, confirm that the action it displays is what
you want, and then click Continue.
4. At the elevated command prompt, type the following command, and then press ENTER:
ntdsutil
5. At the ntdsutil prompt, type the following command, and then press ENTER: snapshot
6. At the snapshot prompt, type the following command, and then press ENTER: activate
instance ntds
7. At the snapshot prompt, type the following command, and then press ENTER: create