Which best describes the difference between 802.11n and 802.11ac?
A. 802.11ac offers more channels over more bands than 802.11n
B. 802.11ac MCS 1 is about twice as fast as 802.11n MCS1
C. 802.11ac offers more modulation schemes than 802.11n
D. 802.11ac 1SS MCS 9 is allowed over a 20, 40, 80 and 160 MHz channel, while 802.11n 1SS MCS 9 is only allowed over a 20 or 40 MHz channel.