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': "True about intrauterine fetal death (IUD):a) Gas bubbles in great vesselsb) Halo's sign +vec) Overlapping of skull boned) Decreased amniotic fluid volume \nSelect and explain. \nA. abc, B. ad, C. acd, D. bde", 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]