A Windows Communication Foundation （WCF） service has a callback contract. You are developing a client application that will call this service. You must ensure that the client application can interact with the WCF service. What should you do？ （）

• A、 On the OperationContractAttribute， set the AsyncPattern property value to True.
• B、 On the OperationContractAttribute， set the ReplyAction property value to the endpoint address of the client. For interactive and self-paced preparation of exam 70-513， try our practice exams. Practice exams also include self assessment and reporting features!
• C、 On the client， create a proxy derived from DuplexClientBase（Of TChannel）.
• D、 On the client， use GetCallbackChannel（Of T）.