Answer:
a.auditory ossicles
b.oval window
c.Round window
d.tympanic membrane
Answer is tympanic membrane
Explanation:
The tympanic membrane otherwise called the ear drum is a membrane shaped like a cone,it connects the outside to the inner ear,it serves to convert vibration from air into fluid membrane vibration a good example of mechanical waves for onwatd transmission into the cochlea of the inner ear through the oval window