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': 'A 15% solution of EDTA has a pH of: \nSelect and explain. \nA. 5.5, B. 7.3, C. 7.9, D. 7', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]