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: Social & Preventive Medicine
[{'content': 'Percentage of para–para isomer in it DDT is – \nSelect and explain. \nA. 20–30%, B. 40–50%, C. 60–70%, D. 70–80%', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]