Your network contains an Active Directory forest named adatum.com.
The forest contains a single domain.
The domain contains four servers.
The servers are configured as shown in the following table.

You need to update the schema to support a domain controller that will run Windows Server 2012 R2.
On which server should you run adprep.exe?

A.
Server1

B.
DC3

C.
DC2

D.
DC1

Explanation:
DC3 is the only server that could be assumed to be 64bit
http://technet.microsoft.com/en-us/library/dd464018(v=ws.10).aspx#BKMK_WS2012