Digital signals are robust against interference such as

• A. Noise
• B. Distortion
• C. Attenuation
• D. Reflection

Answer: (A)

Digital signaling is designed to tolerate interference by using discrete 0s and 1s and making decisions with a clear threshold. When the signal is sampled, the receiver decides which bit value was transmitted based on whether the signal sits above or below that threshold. Small, random fluctuations from noise typically don’t push the value across the threshold, so the correct bit can be recovered reliably. This built‑in margin is even stronger in practice because techniques like error detection/correction and periodic signal regeneration clean up any remaining disturbance as the signal travels.

Distortion, attenuation, and reflection can still cause problems, such as timing errors, reduced signal strength, or multipath effects, which can lead to mistakes if severe. But the reason digital signals are described as robust against interference is that noise—the random, unwanted energy that can perturb the signal—is what these discrete, thresholded decisions are especially good at resisting.