You have an Exchange Server 2010 organization.  The organization contains two servers named Server1 and Server2.  Server1 and Server2 have the Mailbox server role and the Hub Transport server role installed. Server 1 and Server2 are members of a database availability group （DAG）.  You need to plan the deployment of Client Access servers to meet the following requirements： .Users must be able to access their mailboxes if a single server fails .Users must not attempt to connect to a failed server  What should you include in your plan？（）

• A、On Server1 and Server2， install the Client Access server role. Implement failover clustering.
• B、On Server1 and Server2， install the Client Access server role. Configure network interface card （NIC） teaming on each server.
• C、Deploy two new Client Access servers. Implement load balancing by using DNS round robin.Create a Client Access server array.
• D、Deploy two new Client Access servers. Implement load balancing by using a Windows Network Load Balancing cluster. Create a Client Access server array.