A network administrator notices that the data transfer rates between devices in a $100$BASE$-$TX Fast Ethernet network are not reaching the expected $100$ Mbps$.$ The network uses switches, and all devices support Fast Ethernet.

What could the network administrator enable to improve the data transfer rates to the expected $100$ Mbps $?$

Autonegotiation on all devices

Full$-$duplex mode on all devices

Replace all Cat $5$ cables with fiber optic cables

Replace switches with hubs