This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nose and PNS, Subject name: ENT
Sinusitis is LEAST involved in 
Select and explain. 
A. Maxillary, B. Ethmoid, C. Frontal, D. Sphenoid
D: Sphenoid
Answer: D: Sphenoid 
Explanation: (Sphenoid) (181- Dhingra 4th)* Most common sinus involved is - Maxillary* Least common sinus involved in - Sphenoid* Order of sequence - Maxillary >ethmoid > frontal > sphenoid