Answer
Check below for the ordering.
Work Step by Step
1) The specific causative agent must be found in every case of the disease.
2) The disease organism must be isolated in pure culture.
3) Inoculation of a sample of the culture into a healthy, susceptible animal must produce the same disease.
4) The disease organism must be recovered from the inoculated animal.
The ordering according to the specified letters is : (c), (a), (d), (b).
