I believe the best answer is the gallbladder.
I hope this helped 
        
                    
             
        
        
        
The build up in the child's ear prevent sound from reaching the eardrum.
        
             
        
        
        
It is not C
I don't think its A
do you have like a lesson or textbook that can help you?
because information like that is going to be in your textbook...