<prompt> Gram Stain is a:Simple stainDifferential stainNegative stainNone  <response>: Ans. b Differential stainRef.: Microbiology by Ananth and Paniker 8th ed.15DIFFERENTIAL STAIN These are positive stain, which divide bacterial population into two different groups by imparting two different colors Gram Stain: it is the most common staining method of bacteriology. It stains cell wall of bacteria. Gram positive appears blue Gram Negative appears pinkred Z-N stain is used to distinguish acid fast bacteria and non-acid fast bacteria. Presence of mycolic acid is responsible for the acid-fast nature of bacteria. 