单项选择题AcompanywantsallIMchatviatheinternettostop.AtechnicianblocksIRCtrafficwithatrafficshapingdevice,yetIMchatremainsuseable.Whichofthefollowingshouldatechniciandonext?()
A.Block both IRC and ICMP
B.Utilize SNMP to identify IM users
C.Contact the IM carrier to request the IM account be disabled
D.Change the shaping setting to allow minimal traffic to reduce port hopping