This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urology, Subject name: Surgery
[{'content': 'Thimble bladder is seen in all except \nSelect and explain. \nA. TB, B. BPH, C. Malignancy, D. Schitosomiasis', 'role': 'user'}, {'content': "Answer: B \nExplanation: Thimble bladder or systolic bladder is inability of the bladder to relax and distend and so inability to retain the urine as required. Causes include Tuberculous cystitis, Schistosoma haematobium, Interstitial cystitis, \x02Radiotherapy, \x02Malignancy, \x02Previous bladder surgery. Bladder is fibrotic and contracted, with difficulty in dilating and accommodating urine as needed. Bladder capacity is less than 100 ml (60 ml). Reference : page 1033 SRB's manual of surgery 5th edition", 'role': 'assistant'}]