Answer:
I know this is late, but for the people looking for the answer, its carbon and hydrogen
Its "C"Oxygen because it is used as oxidative phosphorylation
The cyanobacteria changed the composition of the earth’s atmosphere by evolving oxygen in what is referred to as the Great Oxygenation Event. This also allowed the ozone to be formed and block off most of the UV rays that are destructive to genetic material. Life was, therefore, also able to exist on land other than in water.
Your answer would be C because A affects the natural environment and can cause harm to it, B would affect the surrounding animal population and cause imbalances in biodiversity if they are not able to eat the foods they are used to, and D is not much of a benefit since you are losing the flavor that is naturally in the plants.