Which of these is used by the Cisco IP phone to relay to the switch the information regarding how much power is needed?

Which of these is used by the Cisco IP phone to relay to the switch the information regarding how much power is needed?
A. the Cisco Discovery Protocol
B. IEEE 802.10 protocol
C. Cisco IP phones always use a fixed power consumption hased on the resistor, which is specific to the model
D. The switch model determines how much power is consumed by the different phone models