Your company has an Active Directory forest named contoso.com.  You plan to deploy an Exchange Server 2010 organization that will contain two servers.  Each server will have the Client Access server role， the Hub Transport server role， and the Mailbox serverrole installed.  You plan to add both servers to a database availability group （DAG）.  You need to recommend a high-availability solution for the Client Access server role.  Your solution must ensure that users are not prompted to authenticate if a Client Access server becomesunavailable.  What should you recommend？（）

• A、Create and configure a Client Access server array， and then install a hardware load balancer.
• B、Create and configure a Client Access server array， and then install Windows Network Load Balancingon both servers.
• C、Deploy Microsoft Internet Security and Acceleration （ISA） Server 2006， and then implement DNS round robin.
• D、Deploy Microsoft Internet Security and Acceleration （ISA） Server 2006， and then install Windows Network Load Balancing.