According to Koch's Postulates, in Order to Prove That Any

According to Koch's postulates, in order to prove that any given infectious agent causes a certain disease a scientist must satisfy all of the following requirements EXCEPT:

A) the pathogen must be present in every case of the disease.
B) the same pathogen must be reisolated in the diseased experimental host.
C) the cultured pathogen must cause the disease when inoculated into a healthy and susceptible experimental host.
D) the disease is caused by a combination of infectious pathogens and environmental factors.
E) the pathogen must be cultured and isolated from every case of the disease.