The correct answer is option 1: Bacillus. Rod-shaped bacteria are called bacillus. Bacillus bacteria are characterized by their elongated shape resembling rods. They are classified as such based on their morphology or shape. Bacillus bacteria can be found in various environments, including soil, water, and even the human body. They are capable of causing diseases such as anthrax and food poisoning. Some species of bacillus bacteria are also used in biotechnological applications, such as the production of antibiotics and enzymes. It is important to note that option 2, Spirillum, refers to a type of bacteria that is spiral-shaped, option 3, Coccus, refers to bacteria that are spherical in shape, and option 4, Coma, is not a term used to describe bacteria morphology.