Answer:
A- reforestation (replanting trees in a deforested area)
Step-by-step explanation:
Deforestation would be the cutting down of trees for things like paper products and lumber. The opposite of this would be reforestation, or planting trees to replace the ones cut down.
Deforestation and reforestation create a cycle where one destroys and the other creates, meaning that while we cut down trees, we also plant new ones for future generations, so reforestation is an example of sustainability.