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: Medicine
[{'content': 'Outright or full-blown AIDS is characterized by: \nSelect and explain. \nA. CD4 T-cell<800 cells/mm3, B. CD4 T-cell<600 cells/mm3, C. CD4 T-cell<400 cells/mm3, D. CD4 T-cell<200 cells/mm3', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]