RS-485 is best described as a multipoint communication standard that incorporates which features?

• A. Point-to-point wireless links
• B. High-impedance drivers and receivers
• C. Low-impedance drivers and receivers providing high tolerance to noise
• D. Fiber optic transmission only

Answer: (C)

RS-485 is a multipoint wired bus that uses differential signaling on a twisted pair. The driving side is designed with low output impedance to push the differential voltage along the line, while the receiving side uses high-impedance inputs to sense that signal without loading the line excessively. This combination, along with proper termination and biasing, gives strong resistance to noise and allows many devices to share the same bus over long distances. The description that emphasizes low-impedance drivers and receivers providing high tolerance to noise captures this key behavior: robust signal integrity on a multi-node network. It’s not wireless, not fiber optic, and the idea of high-impedance driving is not what RS-485 uses to achieve its reliability.