Which standard or standards must the wireless products support?

A network architect is redesigning a wireless network. The architect begins by analyzing the number of spatial streams supported by APs of various vendors as well as the wireless devices currently in the network, if the company wants to ensure that new wireless design, including user wireless devices, support Multi-User MIMO (MU-MIMO).

Which standard or standards must the wireless products support?
A . Only 802.11ax and 8011.ac
B . Only 802.11ax
C . Only 802.11ax,802.1lac, and 802.l1n
D . Only 802.11ax,802.11ac, 802.11n, and 802.11a

Answer: C