This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: ENT
Prolonged blockade of Eustachian tube leads to ? 
Select and explain. 
A. Atelectatic ear, B. Cholesteatoma, C. Perforation, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Ans. is'd'i.e., All of the above[Rf Dhingra 6h/e p. 60)Acute tubal blockage - AbsorPtion of ME gases - Negative Pressure in ME - Retraction of TM - Transudate in ME/haemorrhage (acute OME) - Prolonged tubal blockage/dysfunction - OME (thin watery or mucoid discharge) - Atelectatic ear/Perforation - Retraction pocket/cholesteatoma