The command sudo firewall-cmd --permanent --remove-service=http is correct because it permanently removes the rule allowing HTTP service (which operates by default on port 80) from the firewall configuration using firewall-cmd, the tool for managing firewalld, a firewall service daemon that provides a dynamic firewall management tool with support for network/firewall zones. Removing the HTTP service effectively blocks unencrypted web traffic. The --permanent flag ensures that the change persists across system reboots. Other options either open ports, set up rules for a different service, or list services, hence they do not achieve the task of blocking HTTP traffic.