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: Gynaecology & Obstetrics
[{'content': 'The pH of vagina in adult women is : \nSelect and explain. \nA. 4.5, B. 6.5, C. 7.5, D. 7', 'role': 'user'}, {'content': 'Answer: A \nExplanation: 4.5', 'role': 'assistant'}]