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': 'Calcification of pulp: \nSelect and explain. \nA. is in response to ageing, B. does not relate to the periodontal condition, C. precedes internal resorption, D. indicates presence of additional canal', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]