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': 'Which of the following drug is not the first line treatment for anovulatory abnormal uterine bleeding in a 13-year-old girl? \nSelect and explain. \nA. Tranexemic acid, B. Mefenamic acid, C. Progesterone, D. Estrogen + progesterone', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. b. Mefenamic acid', 'role': 'assistant'}]