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': 'Number of holes in mosquito net (per sq. inch) – \nSelect and explain. \nA. 50, B. 150, C. 100, D. 200', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]