## Core Concept
Koch's postulates are a set of criteria used to establish a causal relationship between a microbe and a disease. They were developed by Robert Koch in the late 19th century and are fundamental in microbiology and epidemiology. The postulates are: (1) the microorganism must be found in all organisms suffering from the disease, but not in healthy organisms; (2) the microorganism must be isolated from the diseased organism and grown in a pure culture; (3) the cultured microorganism should cause the disease when introduced into a healthy organism; and (4) the microorganism must be re-isolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent.

## Why the Correct Answer is Right
The correct answer, which is not directly provided, must correspond to an option that fully satisfies Koch's postulates. This means the microorganism in question has been: found in every case of the disease, isolated and cultured, shown to cause the disease when introduced into a healthy host, and re-isolated from the diseased host. This rigorous set of criteria helps establish causation rather than just association between a microbe and a disease.

## Why Each Wrong Option is Incorrect
- **Option A:** This option does not fulfil all criteria of Koch's postulates, possibly lacking evidence of causation when introduced into a healthy host or re-isolation.
- **Option B:** Similarly, this option might not meet one or more of the postulates, such as not being found in all diseased organisms or not being able to be grown in pure culture.
- **Option C:** This could be incorrect if it fails to satisfy the condition of causing the disease when introduced into a healthy host or if it cannot be re-isolated.

## Clinical Pearl / High-Yield Fact
A classic example that fulfils Koch's postulates is *Mycobacterium tuberculosis*, the causative agent of tuberculosis. The fulfillment of these postulates for *M. tuberculosis* was pivotal in establishing it as the cause of TB. This is a high-yield fact because it illustrates a well-known application of Koch's postulates in establishing microbial causation of disease.

## Correct Answer: D.