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
Paranasal sinuses present at bih ? 
Select and explain. 
A. Frontal and maxillary, B. Ethmoid and maxillary, C. Frontal and ethmoid, D. Sphenoid and ethmoid
B: Ethmoid and maxillary
Answer: B: Ethmoid and maxillary 
Explanation: Ans. is 'b' i.e., Ethmoid and maxillary Maxillary sinus - 4 Develop at bih; completely develop at 9 years Ethmoidal sinus - Develop at bih; completely develop at late pubey Frontal sinus - Develop at 2 year; completely develop at late adolescence Spenoid sinus - Develop at 3-5 years; completely develop at 12-15 years