What is the main type of soil in the Northern Plains?

Correct answer: Alluvial soil

The direct answer is option A: the Northern Plains mainly have alluvial soil. Alluvial soil is material such as sand, silt and clay deposited by rivers and their tributaries. The Indus, Ganga and Brahmaputra river systems have carried sediments from the mountains and spread them over a broad, level region. This repeated deposition formed the fertile Northern Plains. Option A is correct because river deposits are the origin of the main soil type there. Option B, black rock, is not a soil type describing the Northern Plains; black soil is associated especially with basaltic regions. Option C, sandy desert soil, belongs mainly to dry desert areas such as the Thar, not the extensive river plain. Option D, lava soil, is not the standard name for the soil of the Northern Plains and is associated with volcanic parent material. The word alluvial should immediately suggest river-borne deposits. Memory cue: rivers bring, spread and renew alluvium across the Northern Plains.