Which device operates at the data link layer of the OSI model?

The correct choice is the switch, which operates at the data link layer of the OSI model. At this layer, the switch is responsible for managing the MAC addresses of devices on a local network. Its primary function is to receive data frames from devices, determine their destination MAC address, and forward the frames to the appropriate device, thus optimizing data traffic and improving network efficiency.

Switches perform frame switching based on the MAC address table they maintain, making real-time decisions on how to forward traffic. This capability helps to prevent collisions on the network and enhances the overall performance of the local area network (LAN).

In contrast, routers operate at the network layer, which is responsible for routing packets between different networks. Firewalls can function at various layers, but they typically operate at the network layer and above to filter traffic based on rules. Bridges, while they do operate at the data link layer, are generally used to connect two network segments and perform a simpler function than switches, which have more advanced capabilities in managing and directing traffic within a network.