Under the microscope, the bacteria appear a bluish-purple colour. Which class of bacteria are on the slide?

Explanation

Correct option: A (fact) (Gram positive bacteria retain bluish purple dye when being tested). If the bacteria appear bluish-purple under the microscope, it indicates that they have retained the crystal violet stain after the Gram staining procedure. Gram-positive bacteria have a thick peptidoglycan layer in their cell wall, which allows them to retain the crystal violet stain and appear purple. Gram-negative bacteria, on the other hand, have a thinner peptidoglycan layer and are counterstained with a red or pink color. Therefore, the bacteria on the slide are most likely Gram-positive.