This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Congenital Lesions and Stridor, Subject name: ENT
Sinus not present at birth is: 
Select and explain. 
A. Ethmoid, B. Maxillary, C. Frontal, D. None
C: Frontal
Answer: C: Frontal 
Explanation: (c) Frontal(Ref. Cummings, 6th ed., 2874; Scott Brown, 8th ed., Vol 2, page 262)This is the last sinus to develop. It is not present at birth.