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
Sinus not present at birth is - 
Select and explain. 
A. Ethmoid, B. Maxillary, C. Sphenoid, D. Frontal
D: Frontal
Answer: D: Frontal 
Explanation: Development and grwoth of paransal sinuses