This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Virology, Subject name: Microbiology
[{'content': 'In diagnosis of AIDS, criteria include the following except - \nSelect and explain. \nA. CD4<200, B. CD8<500, C. CD4 : CD8 = 1, D. Presence of any of the oppounistic infections tuberculosis, pneumosystic carinii, cytomegalovirus', 'role': 'user'}, {'content': 'Answer: B \nExplanation: CD4<200,CD4-CD8 ratio is reversed&presence of oppounistic infection. REF:MICROBIOLOGY ANANTHA NARAYANAN NINTH EDITION PAGE.577', 'role': 'assistant'}]