How is carbon stored in the biosphere?
a. in the atmosphere as carbon dioxide
b. underground as fossil fuels and calcium carbonate rock
c. in the oceans as dissolved carbon dioxide
d. all of the above

The answer is D. Carbon can be absorbed by the atmosphere which makes A correct. It is also found in fossil fuels, which makes B also correct and C is also true. Therefore D which says all of the above is the correct answer

He should put sand around the spill in order to contain it so that it won't spread