Which mechanism detects if VoWLAN clients are experiencing poor signal-to-noise ratio values and causes the power of APs to increase as needed in order to rectify signal-to-noise issues?

Which mechanism detects if VoWLAN clients are experiencing poor signal-to-noise ratio values and causes the power of APs to increase as needed in order to rectify signal-to-noise issues?
A. CCA
B. RSSI
C. 802.11h
D. CHD
E. QBSS