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': 'Medusa head appearance on abdominal X-ray indicates: \nSelect and explain. \nA. Roundworm, B. Tapeworm, C. Roundworm and tape worm, D. Amoehiasis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Roundworm', 'role': 'assistant'}]