A mountain range that runs parallel to the western coast of the Indian peninsula is known as the Western Ghats. The area has over 7,402 species of flowering plants, 1,814 species of non-flowering plants, 139 mammal species, 508 bird species, 179 amphibian species, 6,000 insects species, and 290 freshwater fish species. Many undiscovered species also exist. Around 325 globally threatened species also occur here. And this makes clear that the Western Ghats are the most biodiversity-rich zone in India.
So, the correct answer is 'Western Ghats'.