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: Dental
Angle of Tip of an endodontic instrument 
Select and explain. 
A. 75 + 15, B. 75 — 15, C. 75 ± 15°, D. 80°
C: 75 ± 15°
Answer: C: 75 ± 15° 
Explanation: None