This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Polycystic Ovarian Syndrome, Subject name: Gynaecology & Obstetrics
[{'content': 'The most common cause of Anovulation is: \nSelect and explain. \nA. Polycystic Ovarian Disease, B. Hyperprolactinemia, C. Premature ovarian failure, D. Low ovarian reserves', 'role': 'user'}, {'content': 'Answer: A \nExplanation: WHO Classification for Anovulation Hypothalamic pituitary failure: Hypogonadotropic Hypogonadism Hypothalamic pituitary dysfunction/PCOS: Normogonadotropic Hypogonadism Ovarian failure: Hypergonadotropic Hypogonadism Hyperprolactinemia Anovulation and ovulatory dysfunction can be caused by a number of factors. The most common cause of ovulatory dysfunction is PCOS. Other potential causes of irregular or absent ovulation: Obesity Underweight Extreme exercise Hyperprolactinemia Premature ovarian failure Perimenopause, or low ovarian reserves Thyroid dysfunction Extremely high levels of stress', 'role': 'assistant'}]