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': 'Which of the following periodontal diseases does not have calculus? \nSelect and explain. \nA. ANUG, B. Chronic adult periodontitis, C. Juvenile periodontitis, D. Periodontal abscess', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]