This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Environment and health, 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: The mosquito net: It offers protection against mosquito bites during sleep. The material of the net must be white. The size of openings should not exceed 0.0475 inches in any diameter. The number of holes in one square inch is 150. Other protective measures against mosquito bites are screening and repellants Park's Textbook of Preventive and Social Medicine, 25th Edition, Pg 833", 'role': 'assistant'}]