You are developing a Windows Communication Foundation (WCF) service. The service
operation takes a customer number as the only argument and returns information about the
customer. The service requires a security token in the header of the message. You need to
create a message contract for the service. Which code segment should you use?

A.
[ServiceContract] public interface IService { [OperationContract] CustomerInformation
GetCustomerInformation(Header header, int customerNumber); } [DataContract] public
class CustomerInformation { ……. } [MessageContract] public class Header {
[MessageHeader] public string SecurityTag; }

B.
[ServiceContract] public interface IService { [OperationContract] CustomerInformation
GetCustomerInformation(Header header, int customerNumber); } [MessageContract] public
class CustomerInformation { } [MessageContract] public class Header { [MessageHeader]
public string SecurityTag; }

C.
[ServiceContract] public interface IService { [OperationContract] CustomerInformation

GetCustomerInformation( CustomerNumber request); } [DataContract] public class
CustomerInformation { } [MessageContract] public class CustomerNumber {
[MessageHeader] public string SecurityTag; [MessageBodyMember] public int
CustomerNumberElement; }

D.
[ServiceContract] public interface IService { [OperationContract] CustomerInformation
GetCustomerInformation( CustomerNumber request); } [MessageContract] public class
CustomerInformation { …… } [MessageContract] public class CustomerNumber {
[MessageHeader] public string SecurityTag; [MessageBodyMember] public int
CustomerNumberElement; }