<prompt> True about Eustachian tube -Length is 36 mm in adults and 1.6 mm to 3 mm in childrenHigher elastin content in adultsVentilatory function of ear better developed in infantsMore horizontal in adults  <response>: Eustachian tube serves to ventilate the middle ear and exchange nasopharyngeal air in the middle ear. In children, ET is relatively narrow. It is prone to obstructionQ when mucosa swell in response to infection or allergic challenge and it results in middle ear effusion 