An Administrator Connects Two Switches Together in a Local Enterprise

An administrator connects two switches together in a local enterprise network. The ports of one switch support Fast Ethernet, while the ports of the other switch support Gigabit Ethernet. Hosts connected to one switch are able to communicate, however communication between the two switches fails. What is the possible reason for this?

A) The ports have disabled auto-negotiation.
B) One port is supporting auto-negotiation, while auto-negotiation is disabled on the port of the other switch.
C) The port of one switch is operating using half duplex mode, while the port of the other switch is using full duplex mode.
D) A Fast Ethernet port cannot communicate directly with a Gigabit Ethernet port.