This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
[{'content': 'A middle aged woman presented to the OPD with dull abdominal pain for 6 months. CT scan of pelvis showed a 7cm mass involving left ovary with irregular calcifications. The right fallopian tube & ovary are excised. What is the likely diagnosis? \nSelect and explain. \nA. Mucinous cystadenoma, B. Choriocarcinoma, C. Dysgerminoma, D. Mature cystic teratoma', 'role': 'user'}, {'content': 'Answer: D \nExplanation: .', 'role': 'assistant'}]