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: Pediatrics
Cyanosis in a newborn that disappears on crying is seen in? 
Select and explain. 
A. Laryngocoele, B. Unilateral choanal atresia, C. Bilateral choanal atresia, D. Foreign body
C: Bilateral choanal atresia
Answer: C: Bilateral choanal atresia 
Explanation: Bilateral choanal atresia is due to the persistence of bucconasal membrane. Newborn, being a natural nose breather, presents with respiratory obstruction leading to cyanosis. 
However, if the infant cries and takes a breath through the mouth, the airway obstruction is momentarily relieved and thus cyanosis disappears.