A network technician configured a trunk link between SW1 and SW2 to carry VLANs 10, 20, and 30. Users in VLAN 20 report they cannot reach devices on VLAN 20 connected to the other switch, while VLANs 10 and 30 work fine. On SW1's trunk interface, the technician sees the output: 'switchport trunk allowed vlan 10,30'. Which command on the SW1 trunk interface will restore VLAN 20 connectivity without removing VLANs 10 and 30?