Sandra Has Wanted to Be Famous Ever Since She Was

Sandra has wanted to be famous ever since she was a little girl, and she will do anything to be on TV. Her latest obsession is the X-Factor. Sandra is determined to be on the show despite not being the best singer. Her audition does not go as well as she would have hoped and Simon Cowell, one of the judges on the show, makes some nasty comments towards her. Those comments do not deter Sandra, and she even talks back to Simon Cowell.
-Simon Cowell tells Sandra to sing in lower decibels.Therefore,he is telling Sandra to alter the ______ of her voice.

A) wavelength
B) intensity
C) loudness
D) amplitude