What operation immediately follows an internal collision between two EDCAFs on an IEEE 802.11 QoS STA?

A.
The EDCAF of higher priority transmits its frame.
B.
Each EDCAF begins a new backoff procedure.
C.
The EDCAF of lower priority sets the retry bit to 1.
D.
An EDCAF frame burst starting with the higher priority frame.
I choose A
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