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': 'Antiprogesterone compound RU-486 is effective for inducing abortion if the duration of pregnancy is: \nSelect and explain. \nA. 63 days, B. 72 days, C. 88 days, D. 120 days', 'role': 'user'}, {'content': 'Answer: A \nExplanation: RU–486, i.e. Mifepristone, is an analogue of the progestin “norethindrone”, which has strong affinity for progesterone receptors but acts as an antagonist of progesterone.\nGiven alone, the drug was moderately useful in causing abortion of early pregnancy, however the combination of mifepristone with analogue of prostaglandin E1 i.e. misoprostol is very effective. Combination of mifepristone and misoprostol is effective for inducing abortion within 63 days of amennorhea', 'role': 'assistant'}]