Which of the following statements correctly describe the differences between half-duplex and full-duplex Ethernet?（）
- A Full-duplex Ethernet uses CSMA/CD to prevent collisions.
- B Half-duplex Ethernet uses a loopback circuit to detect collisions.
- C A full-duplex Ethernet card allows 20Mbps for data transmission.
- D Full-duplex Ethernet makes use of two pairs of wires for data.
- E An Ethernet hub can operate both half and full duplex simultaneously.