This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fundamentals in Radiology, Subject name: Radiology
[{'content': 'USG is done to visualize all except - \nSelect and explain. \nA. Fluid, B. Bile, C. Blood flow, D. Bone', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Bone has high acoustic impendence , hence USG is not used for bone pathologies', 'role': 'assistant'}]