Koch's postulates are criteria used to establish that

• A. Microbes are found on dust particles.
• B. Microbes can be used to clean up toxic spills.
• C. a specific microbe is the cause of a specific disease.
• D. a specific microbe should be classified in a specific kingdom.

Answer: (C)

Koch's postulates are about proving causation between a microbe and a disease. The idea is to move beyond simply finding a microbe in a diseased person to showing that this microbe actually causes the illness. The framework asks that the microbe be found in all cases of the disease and not in healthy individuals, be able to be grown in pure culture, cause the same disease when introduced into a healthy susceptible host, and then be re-isolated from that host as the same organism. This sequence demonstrates that the microbe is the cause, not just an associated inhabitant. The other options describe microbes in dust, environmental cleanup, or taxonomic classification—things unrelated to proving a specific microbe causes a specific disease.