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': 'When performing endodontic surgery on anterior crowned teeth, the ideal surgical flap design is a \nSelect and explain. \nA. Full thickness rectangular flap, B. Full thickness triangular flap, C. Submarginal Leubke-Ochsenbein flap, D. Submarginal semilunar flap', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]