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': 'Most susceptible to radiations are: \nSelect and explain. \nA. Nucleic acids, B. Nerve cells, C. Muscle cells, D. Epithelial cells', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]