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': 'Radiological investigation in females of reproductive age should be restricted to: \nSelect and explain. \nA. First 10 days of menstrual cycle, B. Last 10 days of menstrual cycle, C. 10-20th day of menstrual cycle, D. Period of menstruation', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. First 10 days of menstrual cycle', 'role': 'assistant'}]