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.