Which item helps compose a living thing rather than being a major component of soil?

You need to learn what the words mean: www.googleguide.com/

A. Rock Fragments - Might be a component of soil, but not a major component.
B. Organic Matter - "Organic" means carbon and compounds of carbon, a major component of soil if you want to grow something in it.
C. Microbes - The word means "little living creatures." They are not a component of soil, but they might live in soil. And they might not.
D. Bacteria - A specific kind of microbe.
E. Chloroplasts - The green part of a living plant, the part that builds sugars to make up the cell walls. "Compose" means "make up".