This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous ENT, Subject name: ENT
Muller's manoeuver is 
Select and explain. 
A. Forceful expiration against closed glottis, B. Forceful inspiration against closed glottis, C. Forceful expiration against open glottis, D. Reverse of Valsalva's maneuver
D: Reverse of Valsalva's maneuver
Answer: D: Reverse of Valsalva's maneuver 
Explanation: Muller's manoeuvre: Used to find the level and degree of obstruction in sleep-disordered breathing. It is performed while using flexible nasopharyngoscope. First, the examiner sees the upper airways at rest and then during the time when the patient makes a maximal inspiratory effo with nose and mouth closed. The base of tongue, lateral pharyngeal wall and palate are examined for collapsibility and then rated from 0 (minimal collapse) to 4+ (complete collapse). Ref: Textbook of ENT, Dhingra; 6th edition; Pg no: 449