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': 'What is the most common oppounistic infection in aids? \nSelect and explain. \nA. Tuberculosis, B. Cryptococcosis, C. Pneumocystitis cannii, D. Histoplasmosis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Globally ,tuberculosis is the most common cause of moality & morbidity in HIV-infected patients . When CD4 count is less than 500cells/cubic millimeter ,tuberculosis may occur in an HIV patient .It is the most common cause of admission in patients with mild immune suppression . Reference: Harrison20th edition pg 877', 'role': 'assistant'}]