Final answer:
Gram-positive rods are the type of bacteria that produce A-B toxins, with Corynebacterium diphtheriae being a prominent example. The correct answer is option c).
Step-by-step explanation:
The type of bacterium that produces an A-B toxin is a gram-positive rod. An A-B toxin is composed of two parts: the A (active) part that is responsible for the toxic effect and the B (binding) part which binds to the host cell. Notable examples of bacteria that produce A-B toxins include Corynebacterium diphtheriae.
Which produces the diphtheria toxin, and various species of Bacillus and Clostridium. These types of bacteria are typically gram-positive, as can be seen with diseases such as diphtheria, caused by Corynebacterium diphtheriae, and botulism, caused by Clostridium botulinum.
Generally, gram-negative bacteria are not typically associated with producing A-B toxins. Therefore, the correct answer to the question is (c) Gram-positive rods. A-B toxins are produced by gram-positive rods.