The appropriate pronoun for this sentence is "he".
The correct answer is D. Both think that in Europe he would be an oddity who would bring them wealth or favor.
In Act 2, Scene 2, Trinculo sees Caliban and perceives him like a monster. People in England would pay good money to see such a freak, says he. Then, when Stephano enters, he also notices Caliban's weird looks, and thinks that he would be a gift worthy of an emperor. Stephano gives him alcohol in order to tame him, reckoning that he would cost even more if he were tame.
On the day of the wedding, Thumbelina goes outside one last time to see the sun, and is saved, at the last possible minute, by her bird friend. He takes her to the land of flowers and drops her in a blossom where there is a tiny prince, just her size, to whom she becomes (happily) married