What are the requirements to ensure that WMM is working effectively'?

These are the correct requirements to ensure that WMM (Wi-Fi Multimedia) is working effectively. WMM is a standard that provides quality of service (QoS) for wireless networks by prioritizing traffic into four categories: voice, video, best effort, and background. To use WMM, both the APs and the controller must be Wi-Fi CERTIFIED for WMM, which means they have passed interoperability tests and comply with the standard. WMM must also be enabled on the APs and the controller, which is usually the default setting. The client device must also be Wi-Fi CERTIFIED for WMM and configured for WMM marking, which means it can tag its traffic with the appropriate priority level based on the application type. The other options are incorrect because they are either not related to WMM or not required for WMM to work. References: https://www.arubanetworks.com/techdocs/ArubaOS_86_Web_Help/Content/arubaos-solutions/wlan-qos/wmm.htm https://www.wi-fi.org/discover-wi-fi/wi-fi-certified-wmm