You are creating a Windows Communication Foundation service by using Microsoft .NET Framework 3.5.
The service host is configured in the following manner. (Line numbers are included for reference only.)
01 <system.diagnostics>
02 <sources>
03 <source name="System.ServiceModel" >
04 <listeners>
05 <add name="DefaultListener"/>
06 </listeners>
07 </source>
08 </sources>
09 </system.diagnostics>
You discover that the trace file is empty.
You need to enable tracing.
Which code fragment should you use to replace the existing code fragment at line 03?
A.
<source name="System.ServiceModel.MessageLogging">
B.
<source name="System.ServiceModel"
switchValue="ActivityTracing"
propagateActivity="true">
C.
<source name="System.ServiceModel"
switchValue="ActivityTracing"
propagateActivity="false">
D.
<source name="System.ServiceModel"
switchValue="Information, ActivityTracing"
propagateActivity="true">