You are developing a Windows Co

单项选择题 You are developing a Windows Communication Foundation (WCF) service that allows customers to update financial data. The service contract is defined as follows. (Line numbers are included for reference only) 01 [ServiceContract] 02 public interface IDataUpdate 03 { 04 [OperationContract] 05 [TransactionFlow(TransactionFlowOption.Mandatory)] 06 void Update(string accountNumber, double amount); 07 } 08 09 class UpdateService : IDataUpdate 10 { 11 [OperationBehavior(TransactionScopeRequired = true, TransactionAutoComplete = false)] 12 public void Update(string accountNumber, double amount) 13 { 14 ... 15 } 16 } 17 You need to ensure that the service is invoked within the transaction. What should you do?（）: A、Replace line 01 with the following code [ServiceContract(SessionMode = SessionMode.NotAllowed)]; B、Replace line 01 with the following code [ServiceContract(SessionMode = SessionMode.Required)]; C、Call the Invoke method of the form and supply a delegate.; D、Call the BeginInvoke method of the form and supply a delegate.

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