Answer - Cyanobacteria aka Algae that contributed in creating O2 for the atmosphere as a byproduct thru Photosynthetic.
Reason - Of course Algae make up mainly the whole world in waters and they do photosynthesis to give off oxygen in the atmosphere.
I would go with 4 that's what makes the most sense to me, and i just learned about this last year so... I hope this helps good luck..
Answer:
D. the nucleus contains the protons and neutrons which takes up most of the mass of the atom
Explanation:
Answer:
The differential equations and the boundary conditions(initial and final)are shown in the attachment
