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': 'All of the following agents may be used for post coital contraception except: \nSelect and explain. \nA. Danazol, B. CuT, C. RU - 486, D. High dose estrogen', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]