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
All are tests to check eustachian tube patency except - 
Select and explain. 
A. Valsalva maneuver, B. Fistula test, C. Frenzel's maneuver, D. Toynbee's maneuver
B: Fistula test
Answer: B: Fistula test 
Explanation: This question can be solved even if we dont know all tests for eustachian tube patency, because we know fistula test is for assessing vestibular functions and not for Eustachian tube patency. Still it is worth while knowing tests for eustachian tube patency.