Which code fragment should you use?

You create a Windows Communication Foundation service by using Microsoft .NET Framework 3.5.
You need to trace the flow of events in the process activities that are located on the server.
Which code fragment should you use?

A.
<source name="System.ServiceModel"
switchValue="Critical"
propagateActivity="true">

B.
<source name="System.ServiceModel"
switchValue="Verbose"
propagateActivity="true">

C.
<source name="System.ServiceModel"
switchValue="Information"
propagateActivity="false">

D.
<source name="System.ServiceModel"
switchValue="Information, ActivityTracing"
propagateActivity="false">