单项选择题 You have a Windows Communication Foundation (WCF) service that accepts the following message contract.[MessageContract(WrapperNamespace="http://www.movies.com", ProtectionLevel=ProtectionLevel.None)] public class Ticket{ [MessageBodyMember(Namespace="http://www.movietheater.com", Order=1)] public DateTime ShowTime = DateTime.Now; [MessageBodyMember(Namespace="http://www.movietheater.com")] public string ReservationName = "Smith"; [MessageBodyMember(Namespace="http://www.movietheater.com")] public int NumberOfSeats = 0;} You need to ensure that the client sends a SOAP body that is accepted by the service.（）

单项选择题 You are creating an application that consumes a Windows Communication Foundation (WCF) service. The service implements the IService contract. The client application contains the CallbackHandler class, which implements IServiceCallback.You need to ensure that a client proxy is created that can communicate with the service over a duplex channel. Which code segment should you use?（）

单项选择题 You are creating a Windows Communication Foundation (WCF) service that uses claims-based authorization. The following code retrieves the correct claim set.var claims = ServiceSecurityContext.Current.AuthorizationContext.ClaimSets[0];You need to validate that the requesting client application has included a valid DNS value in the claim. Which code segment should you use to retrieve the claim for validation?（）