Final answer:
The 802.11 standard associated with Wi-Fi does not specify a particular medium for a distribution system, so the correct answer is 'None of the above'.
Step-by-step explanation:
The 802.11 standard, which is often associated with Wi-Fi, defines the protocols for wireless LAN (WLAN) communications. It does not specify a particular physical medium for the distribution system; instead, it allows for various media types to be used. While options like 802.3 (Ethernet), 802.15 (related to Bluetooth), and 802.5 (Token Ring) are standards that define different networking technologies, they are not the medium used by the 802.11 distribution system. The correct answer to which medium is used in an 802.11 distribution system is None of the above because the standard does not tie the distribution system to any specific wired medium.