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
Eustachian tube patency seen by - 
Select and explain. 
A. Valsalva, B. Methylene blue test, C. Toyn bee test, D. All the above
D: All the above
Answer: D: All the above 
Explanation: 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