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: Ophthalmology
The most common mucocele of the paranasal sinuses involving the orbit arises from: 
Select and explain. 
A. Frontal sinus, B. Ethmoidal sinus, C. Maxillary sinus, D. Sphenoidal sinus
A: Frontal sinus
Answer: A: Frontal sinus 
Explanation: Ans. Frontal sinus