A WCF service code is implemented as follows. （Line numbers are included for reference only.） For interactive and self-paced preparation of exam 70-513， try our practice exams. Practice exams also include self assessment and reporting features! 01  02 03InstanceContextMode：=InstanceContextMode.Single）> 04Public Class CalculatorService 0506 07Public Function Calculate（ByVal op1 As Double， 08ByVal op As String， ByVal op2 As Double） As Double …  24End Function 25 26End Class You need to increase the rate by which clients get the required response from the service. What are two possible ways to achieve this goal？ （）

• A、
• B、
• C、
• D、Require the clients to use async operations when calling the service.