This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Congenital Lesions and Stridor, Subject name: ENT
During inspiration the main current of air flow in a normal nasal cavity is through: 
Select and explain. 
A. Middle part of the cavity in a parabolic curve, B. Lower part of the cavity in a parabolic curve, C. Superior part of the cavity in a parabolic curve, D. Through olfactory area
A: Middle part of the cavity in a parabolic curve
Answer: A: Middle part of the cavity in a parabolic curve 
Explanation: (a) Middle part of the cavity in a parabolic curve(Ref. Cummings, 6th ed., 626)The main current of airflow passes through the middle part of the nose in a parabolic curve both during inspiration and expiration.