You are creating a Windows Communication Foundation service by using Microsoft .NET Framework 3.5.
You write the following code fragment in the service configuration file.
(Line numbers are included for reference only.)

01 <System.serviceModel>
02 …
03 <behaviors>
04 <ServiceBehaviors>
05 <behavior name="CalculatorServiceBehavior">
06 <CustomServiceBehavior/>
07 </behavior>
06 </ServiceBehaviors>
09 </behaviors>
10
11 </System.serviceModel>

You need to register the custom service behavior in the service configuration file.
Which code fragment should you insert at line 10?

A.
<behaviorExtensions>
<add name="CustomServiceBehavior" Type="CustomBehavior.CustomServiceBehaviorSection, CustomBehavior, Version=1.0.0.0, Culture=neutral, PublicityToken=null" />
</behaviorExtensions>

B.
<extensions>
<add name="CustomServiceBehavior" Type="CustomBehavior.CustomServiceBehaviorSection, CustomBehavior, Version=1.0.0.0, Culture=neutral, PublicityToken=null" />
</extensions>

C.
<behaviorExtensions>
<extensions>
<add name="CustomServiceBehavior" Type="CustomBehavior.CustomServiceBehaviorSection, CustomBehavior, Version=1.0.0.0, Culture=neutral, PublicityToken=null" />
</extensions>
</behaviorExtensions>

D.
<extensions>
<behaviorExtensions>
<add name="CustomServiceBehavior" Type="CustomBehavior.CustomServiceBehaviorSection, CustomBehavior, Version=1.0.0.0, Culture=neutral, PublicityToken=null" />
</behaviorExtensions>
</extensions>