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 test for measuring Graffian follicle Maturation is : \nSelect and explain. \nA. Fern test, B. Endometrial biopsy, C. Transvaginal ultrasonography, D. Abdominal sonography', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Transvaginal ultrasonography', 'role': 'assistant'}]