Which of the following is commonly used as a communication device in modern technology?

A router is commonly used as a communication device in modern technology because it facilitates the connection and communication between different devices on a network. It manages data traffic by directing data packets between computers and other devices, such as smartphones and tablets, allowing them to access the internet and communicate with each other. This functionality is crucial in both home and enterprise environments, enabling various devices to share a single internet connection and work collaboratively.

While printers, monitors, and scanners are essential devices in information technology, their primary functions revolve around specific tasks rather than facilitating network communication. Printers produce physical copies of documents, monitors display visual output from computers, and scanners convert physical documents into digital formats. These devices do not play a role in routing data across a network, which is the key function of a router, making it the best answer in the context of communication devices in modern technology.