You create an application by using Microsoft Visual Studio .NET 2008 and the .NET Framework 3.5.
You are designing a data contract for a Windows Communication foundation (WCF) service that will be hosted by the application.
You need to ensure that the data contract meets the following requirements:
– It does not support Schema versioning.
– It allows additional contract and additional elements to be included over time.
– It allows the client applications to submit messages that contain additional elements without error.
What should you do?

A.
Use the IsRequired property.

B.
Use the DataMemberAttribute attribute.

C.
Implement the IMetadataExchange interface.

D.
Implement the IExtensibleDataObject interface.