This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ear, Subject name: ENT
[{'content': 'Toynbee test is used to the function of - \nSelect and explain. \nA. Eustachian tube, B. Tympanic membrane, C. Middle ear, D. Semicircular canal', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Eustachian tube Tests for Eustachian tube patency* Valsalva test* Methylene blue test* Sonotubometry* Politzer test* Toynbee test* Frenzel maneuver* Catheterization* Inflation - Deflation test", 'role': 'assistant'}]