Does someone know the answer? The word part micro comes from a Greek word that means "small."

Based on this information, what does the word microorganism mean as it is used in the passage?

"Biomass is organic material made from plants and animals (microorganisms)." (paragraph 1)

A. a young and growing life form
B. a rare and delicate life form
C. a life form that moves quickly
D. a life form too tiny to be seen​