This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Culture media and method, Subject name: Microbiology
Method used for acid fast staining - 
Select and explain. 
A. Robertson's method, B. Ziehl Neelsen, C. Silver imprignation method, D. Dark ground illumination
B: Ziehl Neelsen
Answer: B: Ziehl Neelsen 
Explanation: Ans. is 'b' i.e., Ziehl Neelsen Acid fast stainingo After staining with aniline dye, acid fast organisms resist decolourisation with acids,o Method most commonly used is modified Ziehl Neelsen.Smear stained by carbolfuschin|Decolourization by 20% sulphuric acid|Counterstaining by methylene blueAcid fast organismsNon acid fast organismsRetain fiischin (red colour)Take colour of methylene blue (blue colour)Acid fastness depends uponMycolic acid Integrity of cell wall