Cisco IDS sensors form the eyes and ears of your Cisco network intrusion detection system.Placing sensors correctly throughout your network is crucial to successfully implementing your Cisco intrusion detection system . Where can an IPS sensor be placed in an enterprise network?（）

A. core layer
B. bridging two VLANs on one switch
C. between two Layer 2 devices withtrunking
D. between two Layer 2 devices withouttrunking