Which feature should be included in the design that will be configured on the WLC running 8.1 or above to ensure anchor redundancy?

An engineer has designed an anchor redundancy for guest clients connecting to SSID with auto-anchor configured. After adding a second Anchor WLC under the SSID mobility anchor list, clients are load-balanced between existing and new anchors instead of having one anchor as active and the other one as standby.

Which feature should be included in the design that will be configured on the WLC running 8.1 or above to ensure anchor redundancy?
A . Auto-Anchor Foreign Mapping
B . AP groups
C . Guest Anchor Priority
D . 802.11r

Answer: C