You have an Exchange Server 2010 organization that contains a single Mailbox server. The
Mailbox server contains two mailbox databases named DB1 and DB2.
You need to restore a backup of DB1.
Users must be able to connect to their mailboxes on DB1 during the restore process.
What should you create first?

A.
a database availability group (DAG)

B.
a Client Access server array

C.
a Recovery Mailbox database

D.
a recovery storage group