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': 'Which of the following are acid fast positive with 20% sulphuric acid: \nSelect and explain. \nA. M. avium, B. M. leprae, C. M. tuberculosis, D. Nocardia', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. (c) M. tuberculosis Features M. tuberculosis M. leprae Acid fastness Resist decolorization by 20% H2SO4 Resist decolorization by 5% H2SO4 Alcohol fastness Present Absent Culture Possible Not possible Niacin Positive (also some strain of M. microti) Negative Generation time 14-15 hours 12-1 3 days Remember:- Nocardia resist 1-4% of sulphuric acid (weakly acid fast).', 'role': 'assistant'}]