Answer :
When fossil fuel is burned it emits carbon dioxide into the air. And the ocean traps CO2, but it needs a good amount of fish to in order to contain. And 20% of Americas carbon dioxide emission is due to excessive farming, although there are other ways to avoid affecting global warming so i think this is the best answer. Deforestation as we all know takes away the balance between oxygen in the air and carbon dioxide so that wouldn't be you answer. I think your best bet is D since the articles i read are dated and there are more ways than one to farm.