Easy. Answer is oxygen because it says which one was missing before any life was on earth. And in order to have life on earth you need oxygen!
:)
1.
B
Photosynthetic organisms require light, in which the sun’s rays can only go so far
2.
C
The energy flow pyramid goes from decomposers to producers, meaning that if producers are dying out due to lack of nutrients, there must be something wrong with the decomposer population
1. Reduced production of waste materials
2. Increased reuse of older materials
3. Use more renewable sources of energy
4. Decrease the rate of fires through alternate means of warmth
5. Burn down less forests and find better means of farming
