Certkiller is having an Active Directory Rights Management Service （AD RMS） server. 
Users machines are running Windows Vista and an Active Directory domain is configured at Microsoft Windows Server 2003 functional level.  Users are complaining that they cannot protect their documents. You need to configure AD RMS so that users are able to protect their documents.
What should you do（）

A.Use a group policy to install the AD RMS client computers
B.Add the ADRMSADMIN account to the local administrators group on the computers
C.Add the ADRMSSRVC account to the local administrators on the AD RMS server
D.Establish an e-mail account in Active Directory Domain Services （AD DS） for each user
E.Upgrade the active directory domain to the functional level of Windows 2008 server