The correct answer is: Ganges.
The Ganges river valley is one of the most important archaeological sites in India. It contains numerous prehistoric sites that date back to the Stone Age. These sites provide valuable insights into the early history of India and the development of human civilization.
The Son river valley is also an important archaeological site, but it does not contain as many prehistoric sites as the Ganges river valley. The Gandak river valley and the Kosi river valley are not as important archaeological sites as the Ganges and Son river valleys.
The Ganges river is the longest river in India and one of the longest rivers in the world. It flows through the northern states of India and into Bangladesh. The Ganges is a sacred river for Hindus and is considered to be a symbol of life and fertility.
The Son river is a tributary of the Ganges river. It flows through the states of Bihar, Jharkhand, and Madhya Pradesh. The Son is an important source of water for irrigation and drinking water.
The Gandak river is a tributary of the Ganges river. It flows through the states of Bihar, Nepal, and Uttar Pradesh. The Gandak is an important source of water for irrigation and drinking water.
The Kosi river is a tributary of the Ganges river. It flows through the states of Bihar and Nepal. The Kosi is a major river in India and is known for its floods.