This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Emergency Contraception - Ulipristal acetate (UPA), Subject name: Gynaecology & Obstetrics
[{'content': 'Emergency contraceptive contains? \nSelect and explain. \nA. Estradiol, B. Levonorgestrel, C. Estrone, D. PGE.', 'role': 'user'}, {'content': 'Answer: B \nExplanation: ANSWER: (B) LevonorgestrelREF: Shaw 13th ed p. 233"The post coital pill or emergency pill or morning after pill contains levonorgesterol (LNG)"', 'role': 'assistant'}]