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: Surgery
[{'content': 'Treatment of submandibular salivary gland ductcalculi is \nSelect and explain. \nA. Excision of submandicular gland, B. Opening the duct at the frenulum, C. Opening the duct and removal of calculus, D. Excision of gland and duct', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]