What network device is responsible for sending data over the Internet?

The router is the correct choice because it is specifically designed to route data between different networks, particularly over the Internet. It operates at the network layer of the OSI model and uses IP addresses to forward packets to their destination, determining the best path for the data to travel. Routers connect multiple networks together, making it possible for devices within different networks to communicate with each other and access the Internet.

The other devices have different roles: switches operate primarily within a single network segment to connect devices, focusing on MAC addresses for data forwarding. Firewalls provide security by controlling incoming and outgoing network traffic based on predetermined security rules, and hubs simply connect multiple Ethernet devices in a single network segment without any processing or intelligence. This distinction in functionality explains why the router is the pivotal device for sending data over the Internet.