You need to add an additional UPN Suffix

Your network contains one Active Directory forest named contoso.com.
The forest contains two child domains and six domain controllers.
The domain controllers are configured as shown in the following table.

You need to add an additional UPN Suffix.
What should you use?

A.
Set-ADSite

B.
Set-ADReplicationSite

C.
Set-ADDomain

D.
Set-ADReplicationSiteLink

E.
Set-ADGroup

F.
Set-ADForest

G.
Netdom

Explanation:
https://technet.microsoft.com/en-us/library/dd391925(v=ws.10).aspx