The blood flows through the vessels of the heart to keep it going
Fire is not a living thing, and abiotic factors are the factors in an ecosystem that are non-living. So, fire is an abiotic factor in an ecosystem, though its not mentioned alot.
Choice C is most likely to be the right answer!
Diffusion has a major part in this. It has proteins embedded in it that allow molecules to diffuse in and out of the cell up and down its concentration gradient.
