This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Pharmacology
[{'content': 'Drug of choice for polycystic ovarian disease is: \nSelect and explain. \nA. Metformin, B. Estrogen, C. Estrogen and progesterone combination pill, D. Dopamine antagonist', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Metformin has been found to improve ovulation and feility in some infeile women with polycystic ovary. It may be due to the mitigation of insulin resistance and lowering of circulating insulin levels. (Ref. Essentials of medical pharmacology TD Tripathi 7th edition page no.276)', 'role': 'assistant'}]