from burning coal to the atmosphere from plant tissues to coal in the crust from the atmosphere to the sugars in plants from the respiration of fish to the ocean waters
I gave my students this multiple choice question: Which movement of carbon between reservoirs takes the longest to achieve?

Only one answer is correct among these 4 choices:
- from burning coal to the atmosphere
- from plant tissues to coal in the crust
- from the atmosphere to the sugars in plants
- from the respiration of fish to the ocean waters

Could you tell me which one is correct?

from plant tissues to coal in the crust