A WCF service code is implemented as follows. (Line numbers are included for reference only) 01 [ServiceContract] 02 [ServiceBehavior(InstanceContextMode = 03 InstanceContextMode.Single)] 04 public class CalculatorService 05 { 06 [OperationContract] 07 public double Calculate(double op1, string op, double op2) 08 { 09 } 10 } You need to increase the rate by which clients get the required response from the service. What are two possble ways to achieve this goal? (Each correct answer presents a complete solution. Choose two.)（）

• A、
• B、
• C、
• D、