How is the contrast of floods and fertile soil in Himalayan rivers explained?

Correct answer: Floods cause damage but can also deposit alluvial sediments

The direct answer is A: floods can cause damage but can also deposit fertile alluvial sediments. Rivers carry particles such as sand, silt, and clay. During a flood, the river spreads beyond its channel and its velocity often decreases across the floodplain. When moving water loses speed, it cannot carry as much sediment, so some material settles on the land. Repeated deposits can renew floodplain soil and add nutrients, although floods may also destroy crops, homes, roads, and lives. Option A is correct because it presents both sides of the contrast: danger from excess water and fertility from fresh alluvium. Option B is wrong because floods do not always make soil poisonous; their effects depend on the material carried and local conditions. Option C is wrong because floodwater directly transports and deposits soil material. Option D is wrong because floods occur on land and in river valleys as well as in other environments; they are not limited to the sea. The key is to distinguish short-term damage from possible long-term soil benefit. Memory cue: flood means hazard plus deposition—never write only one side when asked about the contrast.