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
In radiobiology, the "latent period" represent the period of time between: 
Select and explain. 
A. 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
D: Radiation exposure and onset of symptoms
Answer: D: Radiation exposure and onset of symptoms 
Explanation: None