Answer:
b. a capsule
Explanation:
The capsule is mainly made up of polysaccharides and surrounds many bacteria. Capsule staining includes mixing of the bacterial cells with dye and spread out in a thin film on a slide. After air-drying, the cells appear as light-colored structures present in a relatively dark blue-black background. This occurs since the dye particles cannot penetrate either the cell or its capsule. Therefore, the given slide with a colorless ring around the cells in a dark background represents the presence of a capsule around the observed cells.
