The Internet is fundamentally a vast, interconnected global computer network. Option C, "A global computer network connecting millions of devices," accurately defines it as a worldwide system of interconnected computer networks that uses standard Internet Protocol Suite (TCP/IP) to serve billions of users. It enables communication and data exchange across the globe.
Option A ("A software used to play games") is incorrect; software for games is an application that might use the Internet, but it is not the Internet itself.
Option B ("A local area network in an office") describes a LAN, which is a small, localized network, not the global Internet.
Option D ("A large computer used in universities") refers to a single machine, not a network of interconnected devices.