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: Unknown
Incidence of mucocele is lowest in 
Select and explain. 
A. Frontal sinus, B. Sphenoid sinus, C. Maxillary sinus, D. Ethmoid sinus
B: Sphenoid sinus
Answer: B: Sphenoid sinus 
Explanation: Paranasal sinus mucocelesmost commonly occur in the third or fourth decades of life with a slight male predilection.
The frontal sinus is most commonly affected followed by the ethmoid sinuses, with reports suggesting 70–90 % of mucoceles occur in these locations.
Ten percent of mucoceles occur in the maxillary sinus and the sphenoid sinus is involved rarely