What is a combined reason for high population in the Ganga plain?

Correct answer: Fertile soil water and level land

The direct answer is Option D: fertile soil, water and level land together support high population in the Ganga plain. Fertile alluvial soil supports productive agriculture. Rivers and groundwater provide water for crops, people and animals. Level land makes ploughing, irrigation, building settlements and constructing roads easier than on steep slopes. Farming can support food, jobs and trade, so settlements become larger and more numerous. Option D is correct because it combines several favourable physical factors. Option A is wrong because severe cold and high slope generally make farming, transport and settlement more difficult. Option B is wrong because sandy land and lack of water are limiting conditions, not advantages. Option C is wrong because inaccessible mountains and poor transport discourage dense settlement. The Ganga plain can still face floods or local problems, but its overall physical suitability explains its high population. Memory cue: fertile soil plus water plus level land attracts people.