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
Acid fastness of tubercle bacilli is attributed to ? 
Select and explain. 
A. Presence of mycolic acid, B. Integrity of cell wall, C. Both of the above, D. None of the above
C: Both of the above
Answer: C: Both of the above 
Explanation: Ans. is 'c' i.e., Both of the above Acid fastness has been ascribed variously to the presence in the bacillus of the unsaponifiable wax (mycolic acid) or to a semipermeable membrane around the cell. It is related to the integrity of the cell wall and appears to be a propey of lipid-rich waxy cell wall. Acid fastness is not a propey of lipids alone but depends also on the integrity of the cell wall. - Ananthanarayan