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.