What type of signal has real magnitudes over its range of definition within a finite range?

The correct answer is that an analog signal has real magnitudes over its range of definition within a finite range. Analog signals are continuous in nature and can represent a vast number of values within a given range. They are characterized by their ability to denote changes in amplitude, frequency, or phase that correlate to measurable physical quantities. For instance, an audio signal captured by a microphone is an analog signal, as it reflects continuous variations of air pressure in a range that corresponds to the sound waves it captures.

In contrast, digital signals represent discrete values, often using binary code, which limits their representation to specific points rather than a continuum. Voice signals, while they can also be analog or digital depending on how they are processed, do not encapsulate the broader spectrum of signal types beyond audio applications. Intelligence, though crucial in processing and interpreting signals, does not itself represent a type of signal in this context. Therefore, focusing on the characteristic of having real magnitudes over a defined finite range leads to the conclusion that analog signals are the correct choice.