Your network contains two Exchange Server 2010 Mailbox servers named Server1 and Server2.Server1 hosts a public folder named Folder1.You need to ensure that Folder1 is available if Server1 is offline.What should you do？（）

• A、From the properties of Folder1， add Server2.
• B、From the properties of Folder1， modify the folder limits.
• C、Add Server1 and Server2 to a Client Access server array.
• D、Add Server1 and Server2 to a database availability group （DAG）.