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': 'The inorganic component of subgingival plaque is derived from \nSelect and explain. \nA. Saliva, B. Gingival crevicular fluid, C. Inorganic matter of tooth, D. Food debris', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]