This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nose and paranasal sinuses, Subject name: ENT
Foul smelling nasal discharge is seen in all except 
Select and explain. 
A. Nasal myiasis, B. Choanal atresia, C. Foreign body in nose, D. Rhinolith
B: Choanal atresia
Answer: B: Choanal atresia 
Explanation: Foul-smelling discharge is seen in Nasal myiasis, Foreign body in the nose, Rhinolith In choanal atresia, there is no foul smelling discharge and it is characterized by mucoid discharge in the nose, absence of air bubble in nasal discharge, failure to pass catheter from nose to pharynx. Ref: Textbook of diseases if ENT; PL Dhingra; the edition, pg no. 181,183