Which feature on the wireless controller should have been incorporated in the design?

A wireless deployment in a high-density environment is being used by vendors to process credit card payment transactions via handheld mobile scanners. The scanners are having problems roaming between access points in the environment.

Which feature on the wireless controller should have been incorporated in the design?
A . RX SOP
B . 802.11w
C . AP Heartbeat Timeout
D . Application Visibility Control

Answer: A

Explanation:

https://www.cisco.com/c/en/us/td/docs/wireless/controller/8-5/configguide/b_cg85/advanced_wireless_tuning.html