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': 'Cobra head deformity is characterstic of – \nSelect and explain. \nA. Posterior urethral valve, B. Ureterocele, C. Bladder tumor, D. Cytitis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Cobra head (Adder head) ureteric orifice is seen in ureterocoel (mc. cause), stone, tumor and following retrograde catheterization.', 'role': 'assistant'}]