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
Which among the following sinuses is most commonly affected in a child - 
Select and explain. 
A. Sphenoid, B. Frontal, C. Ethmoid, D. Maxillary
C: Ethmoid
Answer: C: Ethmoid 
Explanation: None