which of the following scenarios would a Cisco switch supply PoE to an IP phone?

In which of the following scenarios would a Cisco switch supply PoE to an IP phone?

A.
In any cases as long as the switch and IP phone are Cisco products.

B.
If the Cisco switch supportsprestandard PoE and the IP phone supports 802.3af.

C.
If the Cisco switch and IP phone both support a commonPoE method.

D.
Only if both the switch and IP phone use 802.3afPoE.