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
Mycobacterium tuberculosis is diffentiated from other atypical mycobacteria by - 
Select and explain. 
A. Niacin test, B. AFB staining, C. PAS staining, D. None
A: Niacin test
Answer: A: Niacin test 
Explanation: None