Your network consists of a single Active Directory domain. You have a DHCP server named DHCP1 that runs Windows Server 2003 Service Pack 2 (SP2).All client computers run Windows XP Service Pack 3 (SP3). All client computers are configured as DHCP clients.You change the IP address on DHCP1.Users report that they cannot connect to the network. You verify that the client computers do not receive an IP address configuration from DHCP1. You need to ensure that the client computers receive an IP address configuration from DHCP1.  What should you do on DHCP1?（） 

• A、Authorize the server. 
• B、Reconcile the scope. 
• C、Enable conflict resolution. 
• D、Restore the server configuration by using the DHCP snap-in.