You have an Exchange Server 2010 organization.In Site 1 are 5 CAS servers and a CAS array named array1.This Site 1 only has access to internet.In a second site， Site 2， plan to deploy 2 CAS servers and a CAS array named array2.Users connect through OWA inside and outside of the network. You need to configure namespaces for OWA Virtual Directories. What should you do for all CAS in Site 2？（）

• A、Set the internal URL to array2.contoso.com.Set external URL to $null.
• B、Set the internal URL to array2.contoso.com.Set external URL to array1.contoso.com.
• C、Set the internal URL to CAS name.Set external URL to $null.
• D、Set the internal URL to CAS name.Set external URL to array1.contoso.com.