Answer:
Explanation:
Ok so it will be the first one but it migt be the second on for the simple fact that they both use CO2 and O2
I might be wrong because i am working on that to in my Bio class
SUBSTANCE: Material composed of only one kind of matter throughout (same atoms or same molecules) ELEMENT: A substance that cannot be decomposed (broken down) into simpler substances by ordinary chemical means. Examples: gold, iron, carbon, hydrogen, oxygen, nitrogen.