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': 'Best diagnosis of ovulation is by : \nSelect and explain. \nA. Ultrasound, B. Laproscopy, C. Endometrial biopsy, D. Chromotubation', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ultrasound', 'role': 'assistant'}]