This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: CT and MRI of the Kidney, Subject name: Radiology
[{'content': "Cobra head appearance is seen in: \nSelect and explain. \nA. Ureterocele, B. Wilm's Tumor, C. Horse shoe kidney, D. Vesicoureteral reflux", 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans: A (Ureterocele) Ref: Harrison is online. 18th edExplanation:Some Important Features in ContrastRadiographsSpider leg appearance -- Polycystic kidneyCobra head appearance -- UreteroceleFlower vase appearance of ureters -- Horse shoe kidneySandy patches -- Schistosomiasis of bladderSoap bubble appearance -- HydronephrosisApple core lesion on barium -- Ca colonClaw appearance on barium enema -- IntussusceptionSaw tooth appearance -- Diverticula of colonBirds beak appearance of esophagus on barium meal -- AchalasiaCork screw appearance of esophagus on barium meal -- Diffuse esophageal spasmString sign of kantor -- Crohn's disseaseThumb printing sign -- Ischemic colitisEGG SHELL CALCIFICATION------ Silicosis, Sarcoidosis. Scleroderma, Histoplasmosis, Amyloidosis, lymphoma following radiotherapy", 'role': 'assistant'}]