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': 'The best time to do an endometrial biopsy in a patient with suspected endometrial cancer is which of the following? \nSelect and explain. \nA. 9 - 10 day, B. 20 - 21 day, C. 26th day, D. 2nd day', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The endometrial biopsy is done just prior to the expected menstrual period, when the uterine lining is at its thickest. Indications for doing endometrial biopsy are chronic anovulation, abnormal vaginal bleeding, suspected uterine cancer, and infeility. Transvaginal ultrasonography is generally done before obtaining an endometrial biopsy.', 'role': 'assistant'}]