Why are the Northern Plains considered a fertile part of India?

Correct answer: Because alluvial soil is found there

The direct answer is A: alluvial soil is found there. The Northern Plains were formed mainly by sediments deposited by the Indus, Ganga and Brahmaputra river systems and their tributaries. These fine deposits are called alluvium. Rivers renew the soil in many places, and the level land plus water availability supports farming, so the plains are highly fertile. Option A is correct. Option B, only sand, is false because the plains contain rich alluvial deposits, not only sand. Option C, no river, is the opposite of reality; many rivers built and nourish these plains. Option D, sea surrounding the land, is false because the Northern Plains are inland, though some southern and eastern margins approach coastal areas. Memory cue: fertile plains usually point to river-made alluvium.