This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abdominal Radiography, Subject name: Radiology
[{'content': "Central dot sign on CT SCAN - \nSelect and explain. \nA. Caroli's disease, B. Primary sclerosing cholangitis, C. Polycystic liver disease, D. Liver hamartoma", 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Caroli's disease o Central Dot sign on CT or USG is seen in (i) Caroli's disease (most common cause); (ii) Prebiliary cysts; (iii) Obstructive jaundice; and (iv) Periportal lymphedema.", 'role': 'assistant'}]