You develop a Windows Communication Foundation (WCF) service. You enable all performance counters and run multiple calls to the service.The service must isolate session data to each user. You need to monitor the instancing behaviour used in the service. Which performance counter should you monitor?（）

A. ServiceModeService 4.0.0.0\Calls
B. ServiceModeService 4.0.0.0\Instances
C. ASNet StateService \ Server Sessions Active
D. ASNet StateService \ Server Sessions Total