This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Normal Menstruation, Abnormal Menstruation, Menopausal Physiology and forsight of conception, Subject name: Gynaecology & Obstetrics
[{'content': 'Which of the following is a cause of secondary amenorrhea: \nSelect and explain. \nA. Pelvic irradiation, B. Diabetes, C. Kallmann syndrome, D. Imperforate hymen', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Normal ovaries are extremely sensitive to radiotherapy hence pelvic irradiation, given for various pelvic malignancies may cause secondary amenorrhea by causing ovarian failure. Otherwise, the more common causes of secondary amenorrhea in women are pregnancy, polycystic ovarian syndrome, hyperprolactinemia, tuberculosis, uterine synechiae, premature ovarian failure and hypothalamic dysfunction. Pregnancy must be considered in all women of reproductive age with amenorrhea.', 'role': 'assistant'}]