Your network contains a domain controller that runs Windows Server 2008 R2.
You need to reset the Directory Services Restore Mode (DSRM) password on the domain
controller.
Which tool should you use?

A.
Ntdsutil

B.
Dsamain

C.
Active Directory Users and Computers

D.
Local Users and Groups

Explanation:
http://blogs.technet.com/b/meamcs/archive/2012/05/29/reset-the-dsrm-administratorpassword.aspx
To Reset the DSRM Administrator Password
1. Click, Start, click Run, type ntdsutil, and then click OK.
2. At the Ntdsutil command prompt, type set dsrm password.