You are designing a Windows Azure web application.   The application must integrate with on-premise business services.   The business services are running on an on-premise server and cannot be rewritten. The business services are not exposed externally.   You need to recommend an approach for accessing the business services.  What should you recommend？（）  

• A、 Move business service functionality to Windows Azure.
• B、 Connect to the on-premise server from a custom service in Windows Azure.
• C、 Create a VPN connection between the application and the on-premise server.
• D、 Expose the business services to the Windows Azure AppFabricService Bus by using a custom service that configures relay binding.