You’re a network administer and you issue the command (show port 3/1) on an Ethernet port. To  your surprise you notice a non-zero entry in the ’Giants’ column. <br /> What could be the cause of this? ()
A、 IEEE 802.1Q
B、 IEEE 802.10
C、 Misconfigured NIC
D、 User configuration
E、 All of the above