Which class should you use?

A Windows Communication Foundation (WCF) service sends notifications when the service is started and stopped.
You need to implement a client that logs these notifications. Which class should you use?

A.
AnnouncementService

B.
AnnouncementClient

C.
DiscoveryClient

D.
HttpListener

Explanation:
AnnouncementService Class
(http://msdn.microsoft.com/en-us/library/system.servicemodel.discovery.announcementservice.aspx)

AnnouncementEndpoint Class
(http://msdn.microsoft.com/en-us/library/system.servicemodel.discovery.announcementendpoint.aspx)

AnnouncementService
This class listens for incoming messages on a standard announcement endpoint (AnnouncementEndpoint)
and provides event notification when Hello or Bye announcement messages arrive.
You can provide a custom announcement service implementation by deriving from this class.