This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: general microbiology, Subject name: Microbiology
Which of the following are AFB positive with 5% sulphuric acid - 
Select and explain. 
A. M. avium, B. M. leprae, C. M. tuberculosis, D. Nocardia
B: M. leprae
Answer: B: M. leprae 
Explanation: Procedure : 1. The smear is stained by a strong solution of carbon fuchsin with the application of heat 2. It is then decolorized with 20% SULPHURIC ACID and counterstained with a contrasting dye such as methylene blue 3. The acid-fast bacteria retain the fuchsin color while others take the counterstain Mycobacterium leprae resists decolorization with 5% SULPHURIC ACID Ref: Ananthanarayan & paniker's Textbook of Microbiology 9th edition pg no 14