Your company has servers that run Windows Server 2008. All client computers run Windows XP Service Pack 2 （SP2）. Windows 2003 Professional， or Windows Vista. You need to ensure all computers can use the IPv6 protocol. What should you do（）

• A、Install Serivce Pack 4 on all Windows 2000 Professional computers
• B、Upgrade the Windows 2000 professional computers to Windows XP SP2
• C、Run the IPv6.exe tool on the Windows 200 Professional and Windows XP computers
• D、Install Active Directory Client extention （DSClient.exe） on the Windows 2000 Professional and Windows XP computers.