Your network contains an Active Directory forestnamed contoso.com.
The functional levelof the forestis Windows Server 2008 R2.
The forest contains a single domain.
You need to ensure that objects can be restored from the Active Directory Recycle Bin.
Which toolshould you use?

A.
Ntdsutil

B.
Set-ADDomain

C.
Dsamain

D.
Enable-ADOptionalFeature

Explanation:
Reference:
http://technet.microsoft.com/en-us/library/dd379481.aspx
Enabling Active Directory Recycle Bin
After the forest functional level of your environment is set to Windows Server 2008 R2, you can enableActive
Directory Recycle Bin by using the following methods:
Enable-ADOptionalFeature Active Directory module cmdlet(This is the recommended method.)
Ldp.exe