I believe the answer you're looking for is cellular respiration.
Answer:
I think the answer is capital
The effect of human activity on the amount of carbon stored in sinks is that humans are pulling out the carbon and burning it at a fast pace through activities like mining. The has greatly contributed to the effects such as global warming. I therefore, think that humans are supposed to seek for alternate sources of energy to prevent these effects of global warming.
Number 13 is C
Number 14 is C
Number 15 is B
