This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Operative Surgery, Subject name: ENT
FESS means 
Select and explain. 
A. Factual endoscopic sinus surgery, B. Functional endonasal sinus surgery, C. Factual endonasal sinus surgery, D. Functional endoscopic sinus surgery
D: Functional endoscopic sinus surgery
Answer: D: Functional endoscopic sinus surgery 
Explanation: Ans. d (Functional endoscopic sinus surgery), (Ref. Scott Brown, Otolaryngology, 6th ed., 12, 29)Functional Endoscopic Sinus Surgery (FESS) is based on the philosophical concept that function can be restored to the paranasal sinuses and normal structures can be preserved through removal of minimal amounts of tissue. This concept embodies a new understanding of the pathophysiology and development of sinus disease and requires a more delicate, minirealist approach to sinus surgery than the extirpative procedures of the past. These techniques were developed by Walter Messerklinger of Graz, Austria. Uncinectomy is 1st step of FESS.