A firewall is explicitly designed to filter and manage network traffic based on a defined set of security rules. It can block specific IP addresses, manage access through ports, and offer both stateful and stateless packet inspection. Stateful inspection tracks the state of active connections and makes decisions based on the context of the traffic (not just rules applied to individual packets). Other options, like proxies and routers, have traffic management capabilities but are not primarily focused on security and typically lack the sophisticated inspection capabilities of a firewall. A switch, on the other hand, focuses on connecting devices within a network and handling data frames; it doesn't have the capabilities to filter and manage network traffic the way a firewall does.