Which parameter, when enabled on a standalone access point, gives the highest priority to a voice packet even when QoS is not enabled?

Which parameter, when enabled on a standalone access point, gives the highest priority to a voice packet even when QoS is not enabled?

A.
QoS Element for Wireless Phones

B.
IGMP Snooping

C.
WMM

D.
AVVID Priority Mapping