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': "Diagnostic serum markers in Down's syndrome are all except : \nSelect and explain. \nA. Free oestrid, B. Alpha feto protein, C. HCG, D. Progesterone", 'role': 'user'}, {'content': 'Answer: D \nExplanation: Progesterone', 'role': 'assistant'}]