Why are kankar nodules sometimes found in Bhangar land of the Northern Plains?

Correct answer: Because it is older alluvium where calcium deposits form

Direct answer: Option A, older alluvium where calcium deposits form. Bhangar is the older alluvial terrace of the Northern Plains. It lies above the newer floodplain and is not renewed by every annual flood. In places, calcium carbonate accumulates in the soil and forms hard nodules called kankar. Thus the presence of kankar is a characteristic clue for Bhangar, although its distribution can vary locally. Option A is correct because it links old alluvium with calcium accumulation. Option B is wrong because Bhangar is inland alluvial land, not a newly formed sea coast. Option C is wrong because kankar is not glacial ice; it is a calcareous concretion. Option D is wrong because active lava flow is volcanic material and has a different origin, texture, and composition. Memory cue: Bhangar is old; kankar is its familiar clue.