Answer:
B) are disease-causing microbes
Step-by-step explanation:
The pathogen is a scientific term used in biology which refers to the germs or the organisms which causes a disease. The pathogens cause disease only when they enter the host's body and the immune system of the host gets weakened to provide protection against that pathogen.
The pathogen which causes diseases belongs to virus, bacteria, fungi and the parasites.
Thus, Option-B is the correct answer.