The answer would most likely be C
Answer:
the element oxygen , represented by the symbol o, is classified as a pure substance
Sediment - rock that has formed from sediment deposited by water or air
Deposition - the geological process in which sediments, soil and rocks are added to a landform or land mass
Environment - the surroundings or conditions in which a person, animal, or plant lives or operates
Global warming. Not reversing it, because that would most likely cause an ice age, but keeping it under control.