Which one of the following is an example of endemic species?

Endemic species is like a local resident of a particular place and is found naturally only in that specific area.

The Nicobar pigeon is a beautiful bird with a unique combination of colors. It's named after the Nicobar Islands, a group of islands in India. This bird is mainly found in these islands and a few nearby areas. Since its natural home is restricted to such a small region, it's an excellent example of an endemic species. It's like saying this bird belongs specially to the Nicobar Islands, and it doesn't naturally live in large regions elsewhere.

The Asiatic Buffalo, also known as the water buffalo, is found in several countries across Asia, not just one specific region. So, it's not restricted to just one narrow geographical area.

Hornbills are a type of bird, and there are many different species of hornbills found in various parts of the world, from Africa to Asia. Because they're spread out in various places, they're not endemic to one specific small region.

The Blackbuck is a type of antelope found mainly in India. While it primarily lives in India, its range is quite vast and not restricted to a tiny area, so it doesn't fit the strict definition of being endemic.