The northern plains of India are densely populated mainly due to which one of the following geographical factors?

Landform

The correct answer is Option (1) → Landform

The northern plains of India are formed by the alluvial deposits of rivers like the Ganga, Yamuna, and Brahmaputra. These plains have fertile soil, a flat surface, and abundant water supply, making them ideal for agriculture and human settlement. The level landform supports dense population due to ease of cultivation, construction, and transportation.