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': 'Which among the following is the best diagnostic method for finding out ovulation? \nSelect and explain. \nA. Ultrasound, B. Laparoscopy, C. Endometrial biopsy, D. Chromotubation', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The finding of secretory endometrium confirms ovulation. The use of an endometrial biopsy (EMB) near the end of the luteal phase can provide reassurance of an adequate maturational effect on the endometrial lining. Within 48 hours of ovulation, the cervical mucus changes under the influence of progesterone to become thick, tacky, and cellular, with loss of the crystalline fernlike pattern on drying. Ref: Ghadir S., Ambasumyan G., DeCherney A.H. (2013). Chapter 53. Infeility. In A.H. DeCherney, L. Nathan, N. Laufer, A.S. Roman (Eds), CURRENT Diagnosis & Treatment: Obstetrics & Gynecology, 11e.', 'role': 'assistant'}]