Answer:
A. Destruction of terrestrial biota
Explanation:
all the other answers would decrease the carbon output. thickening of ocean sediments reinforces a carbon reservoir (which stores carbon), reduction in the use of fossil fuels would reduce the amount of carbon emissions, increase in marine biota = increase in carbon storage because marine biota is also a carbon reservoir.
Destruction of terrestrial biota would cause excess output because terrestrial biota is a carbon reservoir, and all of that carbon would be released into the carbon cycle.
