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': 'Ovulation coincides with: \nSelect and explain. \nA. High estrogen & high progesterone, B. LH surge, C. Low estrogen & high progesterone, D. Progesterone peak', 'role': 'user'}, {'content': 'Answer: B \nExplanation: LH surge', 'role': 'assistant'}]