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

The correct answer is B. leftwards.

Voice-balance is a setting that controls the balance of the left and right channels in a stereo mix. A value of “left” would cause the sound to be output only from the left channel, while a value of “right” would cause the sound to be output only from the right channel. A value of “centre” would cause the sound to be output equally from both channels.

A value of “leftwards” would cause the sound to be output more from the left channel than the right channel, but not exclusively from the left channel. This would not be a correct value for voice-balance, as it would not result in a balanced mix.