The answer is D. corals are imperative to damage
They are multicellular, heterotrophic, they have no respiratory organs, and their digestion is intracellular!
The correct answer is <em></em>ii.
The pharyngotympanic tube or else eustachian tube is a structure of the middle ear, which connects the nasopharynx with the middle ear. The function of this structure is to equalize the pressure and drain the mucus produced by the middle ear.