Your company has an Active Directory forest.  The forest contains two sites named Site1 and Site2.  You plan to deploy Exchange Server 2010 servers in both sites.  You need to plan a high-availability solution for the Mailbox servers that meets the following requirements： .Users must be able to access their mailboxes if a single server fails  .Users must be able to access their mailboxes remotely if a single site becomes unavailable  What should you do？（）

• A、Deploy two Mailbox servers in each site. Install and configure continuous cluster replication （CCR）.
• B、Deploy one Mailbox server in Site1 and one Mailbox server in Site2. Install and configure continuous cluster replication （CCR）.
• C、Deploy two Mailbox servers in each site. Create one database availability group （DAG） named DAG1. Add all Mailbox servers to DAG1.
• D、Deploy two Mailbox servers in each site. Create two database availability groups （DAGs） named DAG1 and DAG2.Add the Mailbox servers from Site1 to DAG1 and the Mailbox servers from Site2 to DAG2.