This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Medical, surgical and gynaecological illness complicating pregnancy, Subject name: Gynaecology & Obstetrics
[{'content': 'Area of mitral valve in severe mitral stenosis during pregnancy \nSelect and explain. \nA. 4-6 cm2, B. 1.5-2.5 cm2, C. 1-1.5 cm2, D. 0.8-1 cm2', 'role': 'user'}, {'content': "Answer: C \nExplanation: Normal area of mitral valve is 4-6cm2 Symptoms usually appear when stenosis <2.5cm2 Severe mitral stenosis is less than 1.5cm2 Critical area is less than 1cm2- High rate of Pulmoary edema(55%) and Arrhythmia(33%) Reference: William's Obstetrics; 24th edition; chapter 49 & DC.Duttas ,9th edition,page 260", 'role': 'assistant'}]