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': 'Patient is being treated with clomiphene for infeility method of choice to look for ovulation : \nSelect and explain. \nA. Serial ultrasound, B. Chest X-ray, C. Serial HCG, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Serial ultrasound', 'role': 'assistant'}]