Which component is critical for digital signal transmission?

The Network Interface Card (NIC) is critical for digital signal transmission because it serves as the essential hardware component that connects a computer or device to a network. It facilitates communication by converting data from the computer’s internal format into a format that can be transmitted over the network. Additionally, the NIC handles the reception of digital signals from other devices, converting them back into a usable format for the computer. Its ability to manage both data encoding and decoding, along with its communication protocols, makes it indispensable for maintaining effective digital signal transmission within a network environment.

Other choices, while they have their individual roles in electrical circuits and communication systems, do not specifically address the necessary connection and interface required for transmitting digital data over a network. For example, transformers are used to change voltage levels, amplifiers boost signal strength, and modulators convert signals from one form to another, but none of these components directly connect devices in a networking context like a NIC does.