This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
[{'content': "Cryptomenorrhea occurs due to : \nSelect and explain. \nA. Imperforate hymen, B. Asherman's syndrome, C. Mullerian agenesis, D. All", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Imperforate hymen', 'role': 'assistant'}]