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: Pathology
[{'content': 'What is the pH at which initiation of caries begins? \nSelect and explain. \nA. 4.3 - 4.5, B. 5.2 - 5.5, C. 4.9 - 5.1, D. 3.5 - 4. 5', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]