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': 'In 40 days of the menstrual cycle, the ovulation occurs at : \nSelect and explain. \nA. 14th day, B. 20th day, C. 26th day, D. 30th day', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]