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': "All are causes of primary amenorrhea EXCEPT \nSelect and explain. \nA. MRKH syndrome, B. Sheehan's syndrome, C. Kallmann's syndrome, D. Turner's syndrome", 'role': 'user'}, {'content': "Answer: B \nExplanation: Sheehan's syndrome Post paum pitutary necrosis. Occurs as a result of ischemic pituitary necrosis due to severe postpaum hemorrhage Presents as failure to lactate or to resume menses (Secondary amenorrhea) Other presentation: genital and axillary hair loss, asthenia and weakness, fine wrinkles around the eyes and lips, signs of premature aging, dry skin, hypopigmentation and other evidence of hypopituitarism.", 'role': 'assistant'}]