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': 'What is the pressure inside uterus during second stage of labour : \nSelect and explain. \nA. 100-120 mm of Hg, B. 200-220 mm of Hg, C. 300 - 400 mm of Hg, D. 25 mm of Hg', 'role': 'user'}, {'content': 'Answer: A \nExplanation: 100-120 mm of Hg', 'role': 'assistant'}]