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: Surgery
[{'content': 'Amyloid stroma is seen in which Ca thyroid - \nSelect and explain. \nA. Papillary Ca, B. Medullary Ca, C. Anaplastic Ca, D. Follicular Ca', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]