Bacteria mostly act as "Decomposer" 'cause they decompose the dead & decaying matter, back into inorganic materials.
Hope this helps!
While moving in between areas of land glaciers erode the land around them, this eroded land leads to weathering from the sand and rocks eroded. Example The Grand Canyon
I believe its A. I could be incorrect though.
The answer is descent with modification.
Descent with modification practically means that a species have changed appearance wise over long periods of time to adapt to their environments better.
Hey There! The "SI" unit is 0.001 grams! Hope this helps!