The answer is B. It gives a feeling of being trapped and isolated.
First, the story is set on an island which is impossible to escape. This adds to the terror once the reader knows what's going to happen. Also, the island is planned to be a perfect hunting ground.
It is a challenge for the hunter, but if the prey is intelligent, like Rainsford, it provides opportunities for
self-defense and protection, which adds to the suspense of the story.
Hoped I helped!