You are moving a Windows Communication Foundation (WCF) service into production. You need to be able to monitor the health of the service.
You only want to enable all performance counter instances exposed by the ServiceModelService counter group.
Which element should you add to the system.serviceModel section in the application configuration file?

A.
<diagnostics performanceCounters=”ServiceOnly” />

B.
<diagnostics wmiProviderEnabled=”true” performanceCounters=”Off” />

C.
<diagnostics performanceCounters=”All” />

D.
<diagnostics wmiProviderEnabled=”true” />

Explanation:
You can enable performance counters for a WCF service through the app.config configuration file of the WCF service as follows:

<configuration>
<system.serviceModel>
<diagnostics performanceCounters=”All” />
</system.serviceModel>
</configuration>

The performanceCounters attribute can be set to enable a specific type of performance counters. Valid values are
All All category counters (ServiceModelService, ServiceModelEndpoint and ServiceModelOperation) are enabled.
ServiceOnly Only ServiceModelService category counters are enabled.
Off ServiceModel* performance counters are disabled. This is the default value.

Performance Counters
(http://msdn.microsoft.com/en-us/library/ms735098.aspx)