The correct answer is B. host-reachability protocol bgp.

In Cisco VXLAN EVPN deployments on Nexus 9000 switches, the mechanism used to ensure that MAC and IP address information is learned via the control plane is the host reachability protocol using BGP EVPN. When the command host-reachability protocol bgp is configured under the NVE interface, the switch leverages MP-BGP EVPN to advertise and learn endpoint information such as MAC addresses and associated IP addresses. This enables control-plane learning, eliminating the need for data-plane flooding.

The exhibit shows the NVE interface with multicast groups configured, but the requirement explicitly asks for control-plane learning, which is only achieved with BGP EVPN.

Option A (ingress-replication protocol bgp) relates to how BUM (Broadcast, Unknown unicast, Multicast) traffic is replicated, not how MAC/IP learning occurs. Options C and D refer to static methods, which do not provide dynamic control-plane learning.

Therefore, to enable EVPN-based control-plane learning of MAC and IP addresses, the required command is host-reachability protocol bgp, making option B correct.