Identify the incorrect statement

Question $7$ Select one:

A$.$

Gigabit Ethernet retains the standard IEEE $802\mathrm{.}3$ frame format

B$.$

Slot time defines the time during which the transmitting node retains control of the medium

C$.$

Maximum network size for $10$ Mbps systems is $2500$m

D$.$

Maximum network size for $100$ Mbps systems is $2500$m