This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nose and paranasal sinuses, Subject name: ENT
Most definitive diagnosis of sinusitis is by 
Select and explain. 
A. X- ray PNS, B. Proof puncture, C. Sinuscopy, D. Transillumination test
C: Sinuscopy
Answer: C: Sinuscopy 
Explanation: Sinuscopy is a method of Endoscopic sinus observation or surgery using Nose telescope. It involves the evaluation of nasal and sinus passages using the endoscope called Sinuscope. The Sinuscope has a narrow tube with a built-in camera so that the physician can see the internal details of the sinuses. By observing the sinus, it is possible to diagnose the problems and treat properly.