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': "Central dot sign is seen in - \nSelect and explain. \nA. Caroli's disease, B. Primary sclerosing cholangitis, C. Polycystic liver disease, D. Liver hamartoma", 'role': 'user'}, {'content': "Answer: A \nExplanation: Central Dot sign on CT or USG is seen in:\n\nCaroli's disease (most common cause);\xa0\nPrebiliary cysts;\xa0\nObstructive jaundice; and\xa0\nPeriportal lymphedema.", 'role': 'assistant'}]