Answer: Fourth option is correct.
Step-by-step explanation:
Germ theory of disease stated that Diseases are caused by the presence and action of specific microorganisms inside the body.
It says that the pathogens are responsible for causing diseases.
These pathogens are too small to see without the use of microscope attacks human, animals and other hosts.
That pathogens caused infection due to which diseases occur in the body.
Hence, Fourth option is correct.