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: Pathology
[{'content': 'Salivary duct calculi \nSelect and explain. \nA. Produce pain on eating, B. Are commonest in the parotid ducts, C. Are common cause of acute parotitis, D. Are associated with hypercaleaemic states', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]