The correct answer is option 3 - Tamil Nadu. The Todas are an indigenous tribe found in the state of Tamil Nadu in southern India. They primarily inhabit the Nilgiri Hills, which are located in the western part of Tamil Nadu. The Todas have a distinct culture and way of life, with their own language and customs. They are known for their traditional dwellings called "munds," which are barrel-shaped huts made of bamboo and thatch. The Todas are also known for their unique dairy farming practices, as they are traditionally a pastoral community. While Madhya Pradesh, Rajasthan, and Arunachal Pradesh are all states in India, the Todas are not found in any of these states.