The passage describes how life on the island is gradually improving, particularly for birds like Antarctic prions and white-headed petrels. It highlights that these birds are increasing in numbers as pests are controlled on the island. The absence of pests allows the birds to return, breed, and contribute to the ecosystem positively. The passage also mentions how bird droppings add nutrients to the soil, supporting plant growth. Overall, Option B effectively conveys the central theme of the passage - the revival and improvement of life on the island due to the absence of pests and the positive impact on birds and plants. Option A incorrectly suggests an increase in the number of predatory birds, which contradicts the positive developments mentioned in the passage. Option C is incorrect as the passage doesn't explicitly state that this protection is the primary cause of the positive changes. Option D is more general and doesn't specifically address the absence of pests as a crucial factor in the positive transformation mentioned in the passage.