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: Microbiology
[{'content': 'The overall effect of HIV is to gradually impair the immune system by interference with \nSelect and explain. \nA. Helper T lymphocytes, B. Natural killer cells, C. Plasma cells, D. Macrophages', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]