Correct answer: (b) Damodar
Explanation
- A
Chambal
(a) Chambal. Famous for ravines and badland erosion on the Yamuna right bank, not as the textbook fault-valley (rift) drainage.
- B
Damodar
(b) Damodar. The Damodar occupies a rift/fault trough on the Chhotanagpur plateau—the classic Indian example of fault-valley drainage and the old ‘Sorrow of Bengal’ floods. That is the official key.
- C
Gandak
(c) Gandak. A Himalayan snow-fed tributary of the Ganga with alluvial fans, not a peninsular fault trough.
- D
Ramaganga
(d) Ramganga. A Kumaun Himalayan river; drainage is not cited as fault-valley in the same sense as Damodar.
Summary. Official key is (b) Damodar. Fault-valley or rift drainage in Indian school geography is the Damodar trough across Chhotanagpur. Chambal is badlands, Gandak and Ramganga are Himalayan. Honour the stored letter (b).