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': 'In severe heat strain the heat stress index (HIS) is – \nSelect and explain. \nA. 10–30, B. 40–60, C. 70–90, D. 100', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]