You have a single Active Directory domain.   All domain controllers run Windows Server 2003 with Service Pack 1 （SP1）.  You plan to store Windows BitLocker Drive Encryption recovery passwords in Active Directory.    You need to recommend the solution that uses the least amount of administrative effort.   What should you recommend？（）

• A、Extend the Active Directory schema.
• B、Upgrade all domain controllers to Windows Server 2008 R2.
• C、Upgrade all domain controllers to Windows Server 2003 SP2.
• D、Upgrade the domain controller that has the role of operations master to Windows Server 2008 R2.