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': 'Comet tail artefact in USG is seen in \nSelect and explain. \nA. Adenomyomatosis, B. Cholesterosis, C. Porcelain gall bladder, D. Acute cholecystitis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Comet tail artefact is a special finding in Adenomyomatosis.', 'role': 'assistant'}]