This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urogenital System, Subject name: Radiology
[{'content': "Which of the following is characterized by 'Cobra head deformity'? \nSelect and explain. \nA. Cystitis, B. Ureterocele, C. Bladder tumour, D. Posterior urethral valve", 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e. Ureterocele Adder head or cobra head appearance on excretory urography is typical of Ureterocele. Image: IVP Image: USG", 'role': 'assistant'}]