A.Configure the front-end servers in each branch office to be members of a new Active Directory site
B.Configure the back-end servers to have server encryption certificates issued by a commercial certification authority （CA）
C.Configure two back-end servers to be members of a Network Load Balancing cluster. Configure Network Load Balancing for inbound RPC connections
D.Configure multiple front-end servers in each branch office to be members of a Network Load Balancing cluster. Configure Network Load Balancing for inbound HTTPS connections

A.Create a separate storage group and database to contain the customer service mailboxes. Enable circular logging for this storage group
B.Create a separate storage group and database to contain the customer service mailboxes. Set the deleted item retention period for this database to zero
C.Place the customer service mailboxes on a new mailbox store in the storage group that contains the main office user mailboxes. Enable circular logging for this storage group
D.Place the customer service mailboxes on a new mailbox store in the storage group that contains the branch office user mailboxes. Set the deleted item retention period for this database to zero