The Damodar River, option 1, is the correct answer because it flows through a rift valley. A rift valley is a type of valley created due to down warping or sinking of the land between two highlands. The Damodar Valley is an example of a rift valley.

Option 2, the Mahanadi, does not flow through a rift valley. It primarily flows through plains and does not have the characteristics of a rift valley.

Option 3, the Sone River, does have some riffle-pool sequences (a characteristic of some rift valleys), but it is not primarily known for flowing through a rift valley.

Option 4, the Yamuna, also does not flow through a rift valley. It primarily flows through plains and merges with the Ganges at Triveni Sangam, a location not associated with rift valleys.

Hence, option 1 is the correct answer.