You are designing a plan to migrate an existing application to Windows Azure.  The application must use the existing Active Directory Domain Services （AD DS） domain. You need to recommend an approach for joining Windows Azure virtual machines to the domain.  What should you recommend？（）

• A、 Install the Active Directory Certificate Services （AD CS） root certificate into the Enterprise Trust certificate store on each virtual machine.
• B、 Configure Windows Azure Connect.
• C、 Configure Windows Azure AppFabric Access Control.
• D、 Install Active Directory Federation Services （AD FS） in the existing domain.