Your Exchange Server 2007 environment contains a single Hub Transport server and a single Mailbox server. E-mail delivery to large dynamic distribution groups is slow. All MSExchangeADAccess Processes Performance Monitor counters on your Exchange servers display normal results. You need to improve delivery time for messages that are sent to dynamic distribution groups. What should you do?
A.
Add more RAM to the existing Mailbox server.
B.
Add more RAM to the existing domain controllers.
C.
Deploy an additional global catalog server. Configure the existing Hub Transport server to use the new global catalog server.
D.
Deploy a second Hub Transport server. Configure the dynamic distribution groups to use the new Hub Transport server as their expansion server.