Your network contains an Active Directory domain. All domain controllers run Windows Server 2008 R2. Client computers run either Windows XP Service Pack 3 (SP3) or Windows Vista. You need to ensure that all client computers can apply Group Policy preferences.
What should you do?

A.
Upgrade all Windows XP client computers to Windows 7.

B.
Create a central store that contains the Group Policy ADMX files.

C.
Install the Group Policy client-side extensions (CSEs) on all client computers.

D.
Upgrade all Windows Vista client computers to Windows Vista Service Pack 2 (SP2).