The correct answer is: a) Near rivers and fertile plains.
Neolithic settlements in Tamil Nadu are often found near rivers and fertile plains because these areas provide a good source of water and food. Rivers provide a source of water for drinking, irrigation, and transportation. Fertile plains provide a good source of food for growing crops.
Hilly regions are not as good for agriculture as river valleys and plains because they are often steeper and have less fertile soil. Along the coast, there is less land available for agriculture because the land is often used for other purposes, such as fishing and tourism. In deep forests, there is less land available for agriculture because the land is often covered in trees and other vegetation.