To Establish a Link Between a Specific Bacterium and a Skin

Multiple Choice

To establish a link between a specific bacterium and a skin disease, researchers have shown that bacterium was present in sick persons but not in healthy individuals. They isolated the bacterium in a pure culture and demonstrated that experimental healthy animals injected with this culture became sick. What other experiment do researchers need to perform to be absolutely sure that the bacterium is responsible for the disease?

A) Isolate bacterium from an infected sick animal and demonstrate that it is the same bacterium as the one used for infection.
B) Demonstrate that the bacterium belongs to the pathogenic lineage.
C) Demonstrate that the bacterium is not able to live outside of humans or animals.
D) Demonstrate all of the above.
E) No experiments need to be done, because there are enough data to establish that skin disease is caused by the investigated bacterium.