Solution

An ad-hoc network allows devices to connect directly to each other without the need for a central router or switch. This type of network is temporary and is often used in mobile computing where devices need to communicate peer-to-peer for tasks like file sharing or collaborative work in the absence of an established network infrastructure. Why Other Options are Wrong: a) A cellular network relies on centralized towers and routers. c) LAN typically involves wired connections through a router or switch. d) WAN connects devices over a broad geographic area using routers. e) VPN provides secure communication over the internet but still relies on existing network infrastructure.