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: Unknown
[{'content': 'Eustachian tube patency seen by - \nSelect and explain. \nA. Valsalva, B. Methylene blue test, C. Toyn bee test, D. All the above', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., All the above Tests for Eustachian tube patencyValsalva testo Politzer testo Catheterizationo Methylene blue testo Toynbee testo Inflation-Deflation testo Sonotubometry'o Frenzel maneuver", 'role': 'assistant'}]