If the Present Generation Has a Perfect Duty to Preserve

If the present generation has a perfect duty to preserve the planet for future generations, it has to be true that the

A) present generation will be able to meet its needs without compromising the needs of future generations.
B) present generation cannot rationally will that the planet is destroyed, because such a future would be extremely undesirable.
C) present generation cannot rationally will that the planet is destroyed, because that would be conceptually impossible or contradictory.
D) cost for this would be morally acceptable according to a cost-benefit analysis.