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': 'All the following are features of radiation except: \nSelect and explain. \nA. Fluorescein, B. Biological, C. Photographic, D. Non penetrating', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. Non penetrating', 'role': 'assistant'}]