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': 'Anti-retroviral therapy is started when CD4 count is less than \nSelect and explain. \nA. 100, B. 350, C. 200, D. 400', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]