The correct answer is option 4, Western Ghats. The concept of an `ecoregion corridor` aims to connect existing protected areas to create a continuous and sustainable habitat for wildlife. The International Union for Conservation of Nature`s (IUCN) World Commission on Protected Areas (WCPA) endorses and supports this concept. In India, one major project for linking existing protected areas is focused on the Western Ghats region.

The Western Ghats is a mountain range that runs along the western coast of India. It is one of the eight "hottest hotspots" of biodiversity in the world, with a high level of plant and animal diversity. The project aims to establish a network of protected areas and corridors within the Western Ghats to enhance wildlife conservation and promote ecological connectivity.

By connecting the existing protected areas through corridors, it allows for the movement of wildlife and helps to maintain gene flow between populations. This connectivity is crucial for the long-term survival of many species and helps to mitigate the negative impacts of habitat fragmentation. Creating an ecoregion corridor in the Western Ghats is an important step towards conserving biodiversity in India.