Exam 200-301 topic 1 question 252 discussion

PoE switches support Cisco pre-standard PD detection mechanisms, and any Standards based compliant PDs. Most Cisco made PDs, pre-standard or standard, support Cisco Discovery Protocol (CDP). Once power is applied to a port that contains a pre-standard or standard Cisco PD, CDP is used in order to determine the actual power requirement, and the system power budget is adjusted accordingly.

Power Over Ethernet (PoE) - Cisco "... Device Detection and Power Allocation The router will detect a Cisco Pre-standard or an IEEE-compliant PD (Powered Device) when the PoE is enabled and the connected device is not being powered by an AC adapter. After device detection, the router will determine the power requirements based on power classification class. Depending on the available power in the power budget, the router determines if a port can be powered. The router initially allocates this power when it detects and powers the device. Power negotiation using CDP/LLDP protocols happens thereafter. Supported protocols for power negotiation are CDP for Cisco PD, and LLDP for non-Cisco PDs. ..."

if an AP that uses vendor neutral protocol is connected, will not draw power from the switch.

B is correct

How was I supposed to know that?

CDP is used in output power negotiations for POE capable devices; like IP Phones, AccessPoints etc. https://learningnetwork.cisco.com/s/article/cisco-discovery-protocol-cdp-x

B is correct

CDP is correct

B is correct: https://blog.router-switch.com/2012/03/faq-power-over-ethernet-poe-power-requirements/