Final answer:
The strategy of planting trees on land that has previously been cleared of trees would most help minimize the environmental costs of farming oil palms in a rainforest climate, by preventing further deforestation and biodiversity loss. Option a is the correct answer.
Step-by-step explanation:
If the goal is to minimize the environmental costs of farming oil palms in a rain forest climate, the most effective strategy would be to plant trees on land that has previously been cleared of trees. This strategy addresses the serious issue of deforestation and the drastic reduction of biodiversity that often follows the establishment of mono-crop plantations such as those for the production of palm oil.
Adopting this approach means avoiding further destruction of primary forests, which are home to a diverse range of species, many of which do not survive in an oil palm plantation environment. Evidence from studies has shown that only a small fraction of the species found in primary forests can be found in oil palm plantations. By utilizing land that has already been cleared, the impact on biodiversity can be reduced, compared to clearing new forest areas.
Moreover, this practice supports the maintenance of ecosystem services such as soil stabilization and carbon sequestration that previously cleared lands could still offer if they are reforested. It is also better aligned with sustainable development goals and the global efforts to maintain biodiversity and combat climate change. Hence, in terms of environmental costs, choosing to plant on previously cleared land is the better option than dedicating a large area to the unique cultivation of oil palms, which could lead to further habitat loss and species decline.