The correct answer is (a) The Nilgiri Hills.
The Todas are a unique tribal community primarily found in the Nilgiri Hills, a mountain range in southern India. They are a pastoral people who herd buffalo and live in small villages. The Todas are known for their unique culture and traditions, including their elaborate funeral ceremonies.
The Western Ghats are a mountain range in western India. The Eastern Ghats are a mountain range in eastern India. The coastal plains are the flat areas along the coast of India.
The Todas are not found in the Western Ghats, the Eastern Ghats, or the coastal plains. They are only found in the Nilgiri Hills.