Which of the following is an example of a PoE standard?

IEEE 802.3af (PoE), 802.3at (PoE+), and 802.3bt (PoE++) are the PoE standards. The amount of power that can be given per port is a significant difference between the standards. 802.3af can deliver up to 15.4 watts per port, 802.3at can deliver up to 30 watts per port, and 802.3bt can deliver up to 60 watts (Type 3) or 100 watts (Type 4). Because of voltage loss across distance, the power that actually reaches the devices is reduced. The 802.3b standard is an obsolete broadband Ethernet standard. Wi-Fi standards are 802.11 and 802.11ax.