Which feature must be configured to remedy the issue?

A company has an existing Cisco 5520 HA cluster using SSO. An engineer deploys a new single Cisco Catalyst 9800 WLC to test new features. The engineer successfully configures a mobility tunnel between the 5520 cluster and 9800 WLC. Clients connected to the corporate WLAN roam seamlessly between access points on the 5520 and 9800 WLC. After a failure on the primary 5520 WLC, all WLAN services remain functional; however clients cannot roam between the 5520 and 9800 controllers without dropping their connection.

Which feature must be configured to remedy the issue?
A . mobility MAC on the 5520 cluster
B . mobility MAC on the 9800 WLC
C . new mobility on the 5520 cluster
D . new mobility on the 9800 WLC

Answer: B