问题：

[单选]

Your network contains a single Active Directory domain that has two sites named Site1 and Site2.  
Site1 has two domain controllers named DC1 and DC2. Site2 has two domain controllers named DC3  and DC4.  DC3 fails.  
You discover that replication no longer occurs between the sites.  
You verify the connectivity between DC4 and the domain controllers in Site1.  On DC4， you run repadmin.exe /kcc.  
Replication between the sites continues to fail.  
You need to ensure that Active Directory data replicates between the sites.  
What should you do（）

A . From Active Directory Sites and Services， modify the properties of DC3.
B . From Active Directory Sites and Services， modify the NTDS Site Settings of Site2.
C . From Active Directory Users and Computers， modify the location settings of DC4.
D . From Active Directory Users and Computers， modify the delegation settings of DC4.