A network interface port has collision detection and carrier sensing enabled on a shared twisted pair network. From this statement, what is known about the network interface port（）。

• A、This is a 10 Mb/s switch port
• B、This is a 100 Mb/s switch port
• C、This is an Ethernet port operating at half duplex
• D、This is an Ethernet port operating at full duplex
• E、This is a port on a network interface card in a PC