What device is primarily used for sending data packets within a network?

A switch is primarily used for sending data packets within a network because it operates at the data link layer (Layer 2) of the OSI model, making intelligent decisions about how to direct data packets to their intended recipient. It uses MAC addresses to forward data only to the specific device for which the data is meant, rather than broadcasting it to all devices on the network, which enhances efficiency and reduces network congestion.

This targeted approach allows for better overall performance within the network compared to other devices. While routers can route data packets between different networks and modems provide access to the internet by converting signals, and hubs send data to all ports, a switch effectively manages data traffic within a single local area network, making it the correct answer in this context.