A.Create two Exchange Server 2003 computers. Place the mailboxes for main office users on one server， and place the mailboxes for remote users on the other server
B.Create a Network Load Balancing cluster that contains two Exchange Server 2003 computers. Place half of the user mailboxes on one server， and place half of the user mailboxes on the other server
C.Create a Microsoft Cluster Server cluster that contains two Exchange Server 2003 computers. Place all of the user mailboxes on one server and configure the other server as a failover node
D.Create a Microsoft Cluster Server cluster that contains two Exchange Server 2003 computers. Place half of the user mailboxes on one server， and place half of the user mailboxes on the other server

A.Create and configure a one-way recipient connection agreement from Active Directory to Exchange Server 5.5
B.Create and configure a configuration connection agreement between Exchange Server 5.5 and Active Directory
C.Create and configure an inter-organizational recipient connection agreement from Exchange Server 5.5 to Active Directory
D.Create and configure a two-way recipient connection agreement between Exchange Server 5.5 to Active Directory
E.Use Microsoft Identity Integration Server （MIIS） to synchronize objects between Exchange Server 5.5 and Active Directory