You have an Exchange Server 2010 organization. You need to recommend a client access solution that meets the following requirements:
Reduces the time required for users to reconnect to user mailboxes if a single Client Access server fails
Prevents users from being prompted for authentication if a single Client Access server fails

What should you recommend?

A.
Client Access server array and hardware load balancer

B.
database availability group (DAG) and hardware load balancer

C.
failover clustering and database availability group (DAG)

D.
Windows Network Load Balancing and failover clustering