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': 'A 36 years old multigravida at 34 weeks, with previous 2 normal vaginal delivery now presented with unstable lie. The most likely diagnosis it s case is: \nSelect and explain. \nA. Oligohydramnios, B. Placenta pre, C. Pelvic tumor, D. Uterine anomalies', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. b. Placenta pre', 'role': 'assistant'}]