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
Standard light-curing tip has a diameter of: 
Select and explain. 
A. 3 mm., B. 5 mm., C. 8 mm., D. 11 mm.
D: 11 mm.
Answer: D: 11 mm. 
Explanation: Standard light curing tip of QTH light has a diameter of 11mm.