1. IEEE Std 802.11™-2020 (Revision of IEEE Std 802.11-2016).
Section 11.11.10, "Neighbor Report element": This section details the contents of the report, stating, "The Neighbor Report element contains information on neighbor APs... that are candidates for a BSS transition." This confirms the purpose is to provide a list of roaming candidate APs.
Section 9.6.16, "Neighbor Report Action frame format": This section defines the frame used for the request and response, solidifying its role in the AP discovery process for roaming.
2. Cisco, "Radio Resource Management under Unified Wireless Networks," White Paper.
Section: "802.11k," Page 6: The document explains, "With 802.11k, an AP can respond to a client's request for a neighbor list... The client can then use this neighbor list to have a pre-emptive idea of good roam candidates." This directly supports the function described in the correct answer.
3. Aruba Networks, "802.11k, 802.11v, and 802.11r," Technical Note.
Section: "802.11k," Page 2: "The 802.11k protocol provides a mechanism for APs and clients to dynamically measure the available radio resources. APs can provide clients with a list of neighboring APs that are candidates for roaming." This explicitly states the purpose of the Neighbor Request/Report exchange.