B. mass extinctions happen when populations crash due to overpopulation while background extinctions are more likely to result from disease.
C. Mutualism I put the other answer and I got it wrong :(
The best answer would be B
Explanation:
They are opposites because they are the same chemical reaction but reversed. Cellular respiration takes glucose (from nutrient/food) and oxygen (from atmosphere) in order to make CO2 (think about exhaling) and H20 (water).
