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': 'Most malignant carcinoma of the bladder is ? \nSelect and explain. \nA. Malignant villous tumour, B. Solid tumour, C. Carcinomatous ulcer, D. Adenocarcinoma', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Solid tumour Muscle Invasive tumour nearly always solid", 'role': 'assistant'}]