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': 'In valvular heart disease complicating pregnancy the following statements are true except: \nSelect and explain. \nA. A closed mitral valvotomy can be carried out if symptoms of mitral stenosis are severe, B. Open heart surgery is associated with a reduction in fetal loss, C. Mitral regurgitation is usually well tolerated, D. A maternal mortality of 15% has been reported in women with critical aortic stenosis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]