A Windows Communication Foundation (WCF) client uses the following service contract.(Line numbers are included for reference only.) 01 [ServiceContract] 02 public interface IService 03 { 04 [OperationContract] 05 string Operation1(); 06 [OperationContract] 07 string Operation2(); 08 } You need to ensure that all calls to Operation1 and Operation2 from the client are encrypted and signed. What should you do?（）

A. Set the ProtectionLevel property in line 01 to EncryptAndSign.
B. Set the ProtectionLevel property in line 04 and line 06 to Sign.
C. Add a SecurityCriticalAttribute ror each operation.
D. Add a SecunitySafeCriticalAttribute for each operation.