What properties of sound determine the volume of sound? how is it affected by the motion or the location of the sound source?

The property of sound that determine its volume is its AMPLITUDE. The amplitude and the volume of the sound are directly varied. Which means that the larger the amplitude, the larger is the volume and the softer it is if the amplitude is smaller. It is not affected by the motion of the sound source so long as the barriers are not breached. 

Then the answer would be d then