A stateful firewall is optimal for enhancing network security as it not only filters traffic based on state, port, and protocol, but also keeps track of active connections. By monitoring the state of network connections, it can make more informed decisions about which packets to allow or deny, dynamically adjusting to the flow of traffic based on the context of the traffic and sessions. Other options, such as static packet filtering, do not offer the dynamic tracking of connection states, making them less effective in scenarios where comprehensive security and control over both ingress and egress traffic are needed.