This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infection, Subject name: Medicine
[{'content': 'Aids infect: \nSelect and explain. \nA. B cells, B. Helper T cells, C. Killer T cells, D. Regular T cells', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans: bRef: Harrison, 16lhed, p. 1086', 'role': 'assistant'}]