Koch’s postulate is fullfilled by all except
**Core Concept**
Koch's postulates are a set of criteria used to establish a causal relationship between a microorganism and a disease. These postulates were first proposed by Robert Koch in 1890 and are still widely used today to confirm the presence of a pathogen in a particular disease.
**Why the Correct Answer is Right**
Koch's postulates are as follows:
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.
4. The microorganism must be re-isolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent.
These postulates provide a framework for demonstrating the causal relationship between a microorganism and a disease.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not provide any information about Koch's postulates.
* **Option B:** This option is incorrect because it does not specify which part of Koch's postulates is being referred to.
* **Option C:** This option is incorrect because it does not provide any relevant information about Koch's postulates.
* **Option D:** This option is incorrect because it does not provide any relevant information about Koch's postulates.
**Clinical Pearl / High-Yield Fact**
It's worth noting that Koch's postulates are not always applicable in modern microbiology, particularly in cases of viral infections where the virus cannot be cultured.
**Correct Answer: D.**