Which of the following devices is designed to produce a signal that can be transmitted and decoded to reproduce the original digital data?

The device designed specifically to produce a signal that can be transmitted and decoded to reproduce the original digital data is indeed a modem. A modem, short for modulator-demodulator, plays a critical role in digital communications. It converts digital data from a computer into an analog signal for transmission over telephone lines or other types of communication channels. At the receiving end, the modem performs the reverse process, demodulating the analog signal back into digital data that the computer can understand.

This capability to modulate and demodulate signals is essential for enabling communication between digital devices and analog systems, particularly in contexts where internet connectivity is involved. By performing these operations, a modem allows data to be sent and received effectively over various types of infrastructures.

In contrast, while routers, switches, and access points are important networking devices, their primary functions do not include the modulation and demodulation of data. Routers manage traffic between different networks, switches connect devices within the same network for efficient communication, and access points provide wireless connectivity to network devices. Therefore, the modem is the device that directly interacts with data signals to ensure they can be effectively transmitted and reconstructed.