You plan to deploy Exchange Server 2010 on a new server. The server will be a member of a database availability group. You need to identify the operating system that can be installed on the server to support Exchange Server 2010. Your solution must minimize costs.  Which operating system should you identify（）？ 

• A、Windows Server 2003 R2 Standard Edition
• B、Windows Server 2008 R2 Standard Edition
• C、Windows Server 2003 Service Pack 2 （SP2） Enterprise Edition
• D、Windows Server 2008 Service Pack 2 （SP2） Enterprise Edition