Answer:
The correct answer is b) Koch's postulates
Step-by-step explanation:
Koch has given some postulates which determine whether a particular bacteria is a cause of a particular disease or not. The Koch postulates are as follows :
1. In every disease bacteria(microbe) is present.
2. This bacteria can be isolated from the host and can be grown in a pure culture.
3. This pure culture of bacteria if injected in a healthy host then it will cause that specific disease in the healthy host.
4. The bacteria can be recovered from the host again.
Therefore in the given question, Koch principles are applied.