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: ENT
First paranasal sinus to develop at bih is: 
Select and explain. 
A. Maxillary, B. Ethmoidal, C. Frontal, D. Sphenoidal
A: Maxillary
Answer: A: Maxillary 
Explanation: Development of SinusesSinusGestational Month WhenDevelopment StasPresent in ClinicallySignificant SizeFully DevelopedMaxillary2degBihdeg12 yearsdegEthmoid30Bihdeg12 yearsdegFrontal4deg3 yearsdeg18-20 yearsdegSphenoid3deg8 yearsdeg12-15 yearsdeg