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': 'Pulp of involved teeth is vital in the following \nSelect and explain. \nA. Apical cyst, B. Granuloma, C. Apical periodontitis, D. Phoenix abscess', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]