Which of the following is not a appropriate value for voice-volume?

The correct answer is D. .

A voice volume is a measure of how loud a voice is. It is typically measured in decibels (dB). A silent voice is a voice that is not audible, or very quiet. A soft voice is a voice that is not very loud, but is still audible. A hard voice is a voice that is loud and clear. A number is not a valid value for voice volume, because it does not represent a level of loudness.