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': 'In TB immunity is provided by - \nSelect and explain. \nA. CD4+, B. CD 8+, C. IgG, D. IgM', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]