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': 'What is the difference between gingivitis and periodontitis? \nSelect and explain. \nA. Gingival sutcus., B. Periodontal pocket., C. Loss of epithelial attachment, D. Mobility of tooth', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]