The correct answer is option-3: Endemic species. Endemic species refer to those that are restricted to a specific geographic area and are not found anywhere else in the world. These species have evolved and adapted to the unique conditions and habitats of that particular region. Their restricted distribution makes them more vulnerable to threats such as habitat loss, climate change, and human activities. Endemic species are important because they play a crucial role in the functioning of their ecosystems and contribute to biodiversity. Conservation efforts are often focused on protecting and preserving endemic species to ensure their survival and maintain the overall health and balance of their ecosystems.