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
[{'content': 'Standard light-curing tip has a diameter of: \nSelect and explain. \nA. 3 mm., B. 5 mm., C. 8 mm., D. 11 mm.', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Standard light curing tip of QTH light has a diameter of 11mm.', 'role': 'assistant'}]