单项选择题

A.contoso.com.AlldomaincontrollersrunWindowsServer2008.ThedomainfunctionallevelandtheforestfunctionallevelaresettoWindows2000nativemode.YouneedtoensuretheUPNsuffixforcontoso.comisavailableforuseraccounts.Whatshouldyoudofirst()
A.Raisethecontoso.comforestfunctionalleveltoWindowsServer2003orWindowsServer2008.
B.Raisethecontoso.comdomainfunctionalleveltoWindowsServer2003orWindowsServer2008.
C.AddthenewUPNsuffixtotheforest.
D.ChangethePrimaryDNSSuffixoptionintheDefaultDomainControllersGroupPolicyObject(GPO)tocontoso.com.