Final answer:
The best example of a dystopia is option D, where giant force fields prevent people on Earth from using the beaches and seas to protect the oceans.
Step-by-step explanation:
The best example of a dystopia among the given science fiction premises is option D. In this scenario, giant force fields prevent everyone on Earth from using the beaches or seas in order to stop the destruction of the world's oceans. This premise depicts a society that sacrifices personal freedom and enjoyment of natural resources for the sake of environmental preservation.