What is the correct reason for considering the Khadar area more useful for farming in the Northern Plains?

Correct answer: It is new alluvium that keeps getting renewed by floods

The direct answer is A: Khadar is new alluvial soil renewed by floods. Alluvium means fine soil, sand and silt brought and deposited by rivers. In the Northern Plains, newer deposits near active floodplains are called Khadar. Floods may damage crops, but they also spread fresh mineral-rich sediment, so the soil is usually fertile and useful for farming. Option A is correct because it gives both identifying facts: new alluvium and repeated renewal by floods. Option B is wrong because hard granite is a rock, not the loose, fertile river deposit that defines Khadar. Option C is wrong because marine coral is associated with seas and coral formations, not the river-made floodplain soil of Khadar. Option D is wrong because Khadar is generally linked with river deposition and fertility, not a dry sandy desert. The exam clue is “new flood alluvium”; choose Khadar, while older, less frequently renewed alluvium is Bhangar. Memory cue: Khadar is “khadar = नया, flood-fed field.”