Which term is used to describe the stain of bacteria?

A. Aerobic: This describes a bacteria's oxygen requirement, not staining. B. Gram-positive: This refers to the cell wall structure revealed by a Gram stain, a common method for classifying bacteria. C. Cocci: This describes the shape (round) of some bacteria, not staining. D. Bacillus: This is a specific genus of rod-shaped bacteria, not a general term for staining.