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: Anatomy
Aeration of which of the following paranasal sinus occur after bih? 
Select and explain. 
A. Frontal, B. Ethmoid, C. Maxillary, D. Sphenoid
A: Frontal
Answer: A: Frontal 
Explanation: The onset of development of aeration of frontal sinus occur after bih and reaches adult configuration by adulthood. Developmental aeration of paranasal sinuses: Paranasal sinusOnset of developmentAdult configurationMaxillary sinusThird month of gestation12 years of ageSphenoidFouh month of gestationPubeyEthmoidFifth month of gestationPubey Ref: Atlas of Neuroradiologic Embryology, Anatomy, and Variants edited by J. Randy Jinkins page 45.