Final answer:
A firewall is the device that filters network traffic to boost security and performance. It creates a barrier between trusted and untrusted networks, unlike routers, switches, or hubs, which serve different networking functions.
Step-by-step explanation:
The device that filters network traffic in order to enhance overall security and performance is a) Firewall. A firewall is a network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules. A firewall typically establishes a barrier between a trusted internal network and untrusted external networks, such as the internet.
Routers are devices that forward data packets between computer networks, creating an overlay internetwork. A switch connects devices within a single computer network and uses packet switching to receive, process, and forward data to the destination device. A hub is a basic networking device that connects multiple computers or other network devices together, but it does not manage any traffic that comes through it, unlike a firewall.