In which two locations in an enterprise network can an IPS sensor be placed？（）
- Abridging VLANs on two switches
- Bbridging two VLANs on one switch
- Cbetween two Layer 2 devices with trunking
- Dbetween two Layer 2 devices without trunking
- Ebetween a Layer 2 device and a Layer 3 device with trunking