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': 'Normal ratio of CD4 (T4) : CD8 (T8) is \nSelect and explain. \nA. 2:01, B. 1:02, C. 3:01, D. 1:03', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Both CD4+ and CD8+ T cells contain several subsets. The CD4+/CD8+ ratio in the peripheral blood of healthy adults and mice is about 2:1, and an altered ratio can indicate diseases relating to immunodeficiency or autoimmunity. An inverted CD4+/CD8+ ratio indicates an impaired immune system.\xa0\nRef :https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5667733', 'role': 'assistant'}]