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': 'In AIDS there is a deficiency of which cell? \nSelect and explain. \nA. CD2, B. CD3, C. CD4, D. CD8', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]