Which option gives a wrong cause for the Northern Plains?

Correct answer: Cooling of volcanic lava

Answer: D. The Northern Plains were formed mainly by the long-term deposition of alluvium brought by the Indus, Ganga, Brahmaputra, and their tributaries. The Himalaya supplied large quantities of rock debris, and rivers carried and spread this sediment over the subsiding foreland area. A is correct because river-borne alluvium is the main material of the plains. B is correct because the Indus-Ganga-Brahmaputra drainage systems and their tributaries deposited the sediments. C is correct because the plain developed through deposition over a very long period, not through one short event. D is wrong: cooling lava forms volcanic rocks and landforms, whereas the Northern Plains are depositional alluvial plains. Memory cue: ‘Northern Plains = rivers plus alluvium over time,’ not lava.