Final answer:
The computers in a LAN are connected via a network adapter card, which translates data into signals for network communication.
Step-by-step explanation:
The computers in a local area network (LAN) are usually connected to the network via a hardware component called a network adapter card. Neither a broadcast radio, html address, nor network protocol serves as a physical connection device for computers to a LAN. Instead, a network adapter card, often simply called a network card, is installed in each computer to enable it to communicate with the network and other connected devices. This card translates data into signals that can be transmitted over the network's cabling system or wirelessly.