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': 'In radiobiology, the "latent period" represent the period of time between: \nSelect and explain. \nA. Cell rest and cell mitosis, B. The first and last dose in radiation therapy, C. Film exposure and image development, D. Radiation exposure and onset of symptoms', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]