This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General obstetrics, Subject name: Gynaecology & Obstetrics
[{'content': 'Twin Peak sign is characteristic of \nSelect and explain. \nA. Dichorionic Diamniotic, B. Monochorionic Diamniotic, C. Monochorionic Monoamniotic, D. Conjoined twins', 'role': 'user'}, {'content': "Answer: A \nExplanation: Determination of ZygositySonographic Determination:ChorionicityDividing inter-twin membrane thicknessSignDichorionicity> 2mmTwin peak sign or Lambda signMonochorionicity< 2mmT signReference: William's Obstetrics; 25th edition; Chapter 45; Multifetal pregnancy", 'role': 'assistant'}]