You are creating an application using Visual Studio 2010. The application consumes a Windows Communication Foundation (WCF) service.You are adding a service reference to the WCF service. You need to ensure that the generated proxy does not block the calling thread when executing a service method. What should you do when adding the service reference? （）
- A Set the Collection type to ObservableCollection.
- B Select the Reuse types in all referenced assemblies option.
- C Select the Generate asynchronous operations option.
- D Select the Always generate message contracts option.