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
In nasal endoscopy Eustachian tube is examined at? 
Select and explain. 
A. 1st pass, B. 2nd pass, C. 3rd pass, D. 4th pass
A: 1st pass
Answer: A: 1st pass 
Explanation: Ans. is'a'i.e., 1st passNasal endoscopy is done in three passes :-First Pass: Examination of nasal cavity, nasopharynx, opening of eustachian tube, walls of nasopharynx, upper surface of soft palate and uvula, opening of eustachian tube of opposite side opening of nasolacrimal duct and inferior meatus.