Clients on access points within an AP group are not receiving multicast traffic after roaming to another AP within the AP group. Which action maintains multicast connectivity?

A NAS-ID uniquely identifies the AP group to a RADIUS server for authentication purposes and has no effect on multicast traffic forwarding.

NAC out-of-band support is a posture and access control mechanism for endpoint compliance, not a mechanism that affects multicast group membership tracking after roaming.

IGMP snooping allows the switch to listen to IGMP membership reports and track which ports have active multicast subscribers. When a client roams to a new AP, IGMP snooping ensures the switch updates its multicast forwarding table to deliver traffic on the correct port, restoring multicast connectivity without requiring the client to re-subscribe manually.

Applying an ACL on the router serving the VLAN would restrict or permit traffic at Layer 3, but does not address the switch-level multicast forwarding issue caused by roaming.