Which statements accurately describe IEEE 802.11 EDCA collision handling in a WMM compliant infrastructure WLAN?

A.
Data frames from lower priority colliding ACs behave as if there were an external collision on the wireless medium.

B.
Collisions between contending EDCAFs within a QoS STA are resolved within the QoS STA

C.
WMM-compliant applications collaborate within a QoS STA to handle transmission collisions at layer 7 of the OSI model

D.
The WMM specification requires use of RTS/CTS as part of the EDCAF in each QoS STA to avoid internal collisions between applications

E.
Collisions within a QoS STA do not require setting retry bits in MAC headers of MPDUs from lower priority ACs