Why Is It Critical in Microbiology to Understand Eukaryotic Microorganisms

Why is it critical in microbiology to understand eukaryotic microorganisms?

A) because eukaryotic organisms gave rise to prokaryotic cell types.
B) because photosynthetic eukaryotes produce oxygen gas as a by-product thereby providing it for aerobic organisms.
C) because all eukaryotic microbes are pathogens to humans, other animals, and plants.
D) because eukaryotic organisms are the primary producers in all food chains.