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: Pharmacology
[{'content': 'Mifepristone used for medical abortion is: \nSelect and explain. \nA. Anti estrogen, B. Anti progesterone, C. Anti folate, D. Prostaglandin derivative', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]