Which description best matches an analog signal?

• A. A smooth line with continuously changing amplitude.
• B. A series of squares with high and low states.
• C. Two-state on or off.
• D. A random, noisy pattern.

Answer: (A)

Analog signals change smoothly over time, taking a continuous range of values rather than jumping between set levels. That’s why a smooth line with continuously changing amplitude best matches an analog signal—it represents gradual, uninterrupted variation in the signal’s strength. In contrast, a series of squares with high and low states and a two-state on or off depict digital signals, which change in discrete steps. A random, noisy pattern shows irregular fluctuations that aren’t inherently continuous or orderly in the way an ideal analog waveform is. So the flowing, uninterrupted curve captures the essence of analog signaling.