The genus of bacteria that cause anthrax.

• A. Clostridium
• B. Bacillus
• C. Streptococcus
• D. Listeria

Answer: (B)

Anthrax is caused by Bacillus anthracis, a bacterium in the Bacillus genus. Bacillus species are Gram-positive, rod-shaped bacteria that can form endospores, which allows them to persist in the environment and survive harsh conditions. The virulence of B. anthracis comes from toxin-encoding plasmids and a protective capsule that help it cause disease, leading to the classic forms of anthrax. The other genera listed are different types of bacteria with distinct features: Clostridium is also a spore-forming genus but anaerobic and responsible for diseases like tetanus and botulism; Streptococcus consists of Gram-positive cocci in chains that cause strep infections; Listeria are Gram-positive rods that cause listeriosis. The organism linked to anthrax specifically belongs to Bacillus.