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 normal pH of the saliva is about \nSelect and explain. \nA. 5.5, B. 9.5, C. 7.5, D. 8.5', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]