You have an Exchange Server 2010 organization that contains three Mailbox servers named MBX1， MBX2， and MBX3.You configure a journaling mailbox on a server named MBX3.You configure journaling on several mailboxes located on MBX1 and MBX2.You need to ensure that journaling occurs if MBX3 fails.What should you do？（）

• A、Configure an alternate journaling mailbox on MBX2.
• B、Configure a second e-mail address for the journaling mailbox.
• C、Configure the shadow redundancy settings in the organization.
• D、Create a retention tag and then assign it to a new retention policy.