The correct answer is A. Colonialism and imperialism is most clearly shown in The Tempest when Prospero views Caliban as inferior and tries to educate him.
Caliban is truly the native inhabitant of the island, as his mother Sycorax gave birth to him there. Therefore, Caliban has a right to the island -- not Prospero. When Prospero arrives, however, he uses his powers to take over and make Caliban his servant. He views Caliban as a dumb beast and tries to educate him.
Prospero's actions are similar to a strong nation taking over a smaller, weaker one. Therefore, Prospero taking control of Caliban is the best reflection of the theme of colonialism and imperialism in The Tempest.