Which of the following are organisms in an animal's body that help fight off diseases?

Antibodies are specialized proteins produced by the immune system in response to specific pathogens, such as bacteria or viruses. When an organism encounters a foreign agent, the immune system recognizes it as a threat and triggers the production of antibodies tailored to bind to that specific pathogen. This binding helps neutralize the pathogen and marks it for destruction by other immune cells.

Antigens, on the other hand, are the molecules on the surface of pathogens that trigger an immune response but are not directly involved in combating diseases. Antibiotics are substances used to treat bacterial infections but are produced externally and do not originate from the animal's immune system. Enzymes are biological catalysts that facilitate chemical reactions within the body but do not play a direct role in immune defense. Thus, antibodies are the correct answer as they are the direct agents responsible for fighting off diseases within an animal's body.