B) By removing the human element from vast stretches of land, we have the potential to reintroduce species of animals and plants that have long since disappeared.
The speaker provides specific examples of areas of land that are becoming reforested and land that will be vacated by farmers in the near future, suggesting that these areas now have the potential to be restored to their natural state. He also notes that certain species are already beginning to move back across Europe, and suggests that the opportunity to reintroduce even more species, including lost megafauna, should be considered. All this information indicate that there is an opportunity to reintroduce species of animals and plants that have long since disappeared by removing the human element from vast stretches of land.