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': 'Radioactive isotope/substance emits the following radiations except – \nSelect and explain. \nA. Alpha, B. Beta, C. Gamma, D. X–ray', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]