Refer to the topology and router output shown in the exhibit． A technician is troubleshooting host connectivity issues on the switches． The hosts in VLANs 10 and 15 on Sw11 are unable to communicate with hosts in the same VLANs on Sw12． Hosts in the Admin VLAN are able to communicate． The port-to-VLAN assignments are identical on the two switches． What could be the problem?