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': 'Profound mitotic delay occurs when the doses are: \nSelect and explain. \nA. Smaller, B. Larger, C. Intermediate, D. No effect of doses', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Radiation is especially damaging to rapidly dividing cell systems, such as skin and intestinal mucosa and hematopoietic tissues. Irradiation of such cell populations causes a reduction in size of the irradiated tissue as a result of mitotic delay (inhibition of progression of the cells through the cell cycle) and reproductive cell death (usually during mitosis).\nThe three mechanisms of reproductive death are:\n\nDNA damage\xa0\nBystander effect\nApoptosis\n\nNote: Large dose of irradiation causes mitotic delay.', 'role': 'assistant'}]