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': 'Doppler USG in twins is used for: \nSelect and explain. \nA. Twin to twin transfusion, B. Conjoined twin, C. Diagnosis of twins, D. All of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]