Which three statements about firewall modes are correct？ （）
- A A firewall in routed mode has one IP address
- B A firewall in transparent mode has one IP address
- C In routed mode， the firewall is considered to be a Layer 2 dew
- D In routed mode， the firewall is considered to be a Layer 3 device
- E In transparent mode， the firewall is considered to be a Layer 2 device
- F In transparent mode， the firewall is considered to be a Layer 3 device