Sunlight i think thats the answer
The answer is A.
A pure substance is pure, so it cannot be separated in most cases.
D, they can be renewed quickly rather than non renewables in which nonrenewable take millions of years. Biomass is all around us, so is water (hydro) and the sun is around us too.
It is avogrado number. One molecue of magnesium has 6.023 x 10^23 atoms
