Which of the following is NOT a type of wireless network ?

The correct answer is Option D (Ethernet). Ethernet is a wired networking technology that uses physical cables, typically twisted-pair copper or fiber optic strands, to connect devices within a local area network. Unlike wireless standards that transmit data through radio waves or light signals, Ethernet requires a direct physical connection between the network interface card and the switch or router. In contrast, Wi-Fi (Option A) utilizes radio frequencies to enable wireless internet access over a range. Bluetooth (Option B) is a short-range wireless protocol designed for connecting peripherals like headphones and keyboards without cables. NFC (Option C) allows for close-range wireless communication between devices, often used in contactless payments. Since Ethernet relies on physical cabling rather than wireless transmission methods, it is the only option listed that does not qualify as a type of wireless network.