The correct answer is D. voice-rate.
Voice-rate is the speed at which a voice synthesized by a speech media agent will read content. It is measured in words per minute (wpm). A higher voice-rate means that the voice will read content faster, while a lower voice-rate means that the voice will read content slower.
Voice-volume is the loudness of a voice synthesized by a speech media agent. It is measured in decibels (dB). A higher voice-volume means that the voice will be louder, while a lower voice-volume means that the voice will be quieter.
Voice-pitch is the highness or lowness of a voice synthesized by a speech media agent. It is measured in Hertz (Hz). A higher voice-pitch means that the voice will be higher, while a lower voice-pitch means that the voice will be lower.
Voice-stress is the emphasis that is placed on certain words or syllables in a voice synthesized by a speech media agent. It is measured on a scale of 1 to 10, with 1 being the least amount of stress and 10 being the most amount of stress. A higher voice-stress means that the voice will be more emphatic, while a lower voice-stress means that the voice will be less emphatic.