You are designing a Windows Presentation Foundation (WPF) application that accesses a business tier. The business tier is implemented as a Windows Communication Foundation (WCF) service and stores data in a Microsoft SQL Server 2008 database. The WCF service will be accessed by external applications that do not use the .NET Framework. You need to recommend an approach for passing data between layers. What should you recommend?
A. Use custom .NET classes with XML serialization.
B. Use custom .NET classes with binary serialization.
C. Use the DiffGram XML format.
D. Use a DataSet object.
