Cyanosis in a newborn that disappears on crying is seen in?: (A) Laryngocoele, (B) Unilateral choanal atresia, (C) Bilateral choanal atresia, (D) Foreign body
Answer is C. 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.