The correct answer is A. voice-pitch.
Voice-pitch is the fundamental frequency of a sound, which is perceived as how high or low the sound is. It is determined by the size and shape of the vocal cords, as well as the tension in the vocal cords.
Voice-range is the difference between the highest and lowest pitch that a person can sing or speak. It is determined by the length, thickness, and tension of the vocal cords.
Voice-stress is the emphasis that is placed on a particular syllable or word. It is determined by the amplitude of the sound, as well as the duration of the sound.
None of the other options are correct because they do not determine how much variation in pitch or tone will be created by the speech synthesize when reading an element.