This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Contraception, Subject name: Gynaecology & Obstetrics
[{'content': 'A woman was taking progestin only pill for contraception. Which side-effect is not likely to occur : \nSelect and explain. \nA. Acne, B. Amenorrhea, C. Dysmenorrhea, D. Obesity', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Drawbacks of progesterone only pill Irregular bleeding Amenorrhea Weight gain Acne Migraine Headache Depression Ectopic pregnancy Breast cancer Thromboembolism Ref: Shaw Gynecology 17 e pg 266.', 'role': 'assistant'}]