Correct answer choice is :
D) The outer ear has to collect the sound waves and lead them to the middle ear.
The sound waves are produced by a sound root, such as the vibrating diaphragm of a radio speaker. The sound source generates waves in the around the tool. As the reservoir remains to vibrate the tool, the vibrations diffuse away from the root at the speed of sound, thus creating the sound wave. Vibrations in the air are called moving longitudinal waves, which we can hear. Sound waves consist of areas of high and low stress declared condensations and rarefactions, individually.