Ethernet LAN speeds have evolved: 10 Mbps (standard Ethernet, IEEE 802.3), 100 Mbps (Fast Ethernet, 100BASE-TX), 1 Gbps (Gigabit Ethernet), 10 Gbps, and beyond. Traditional office networks operated at both 10 and 100 Mbps, so Both A and B is correct. Modern networks predominantly use Gigabit Ethernet.