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: Radiology
[{'content': 'Bead cystogram is used for the diagnosis of: \nSelect and explain. \nA. Ca bladder, B. Stress incontinence, C. Thimble bladder, D. Diveiculum', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Stress incontinence', 'role': 'assistant'}]