Question

which carries information by copying an original sound?
analog signal
digital signal
volume
frequency

Explanation:

Analog signals represent information by continuously varying physical quantities, such as voltage or current, which can directly copy the original sound's waveform. Digital signals convert information into discrete binary values. Volume is a measure of loudness, and frequency is the number of oscillations per second. Neither volume nor frequency "copy" the original sound in the way a signal does.

Answer:

analog signal