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': 'Maximum penetration is seen with: \nSelect and explain. \nA. cc paicles, B. 13 paicles, C. y paicles, D. Electron beam', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. y paicles', 'role': 'assistant'}]