Why can settlement on a floodplain be risky despite the natural fertility provided by a river?

Correct answer: Because water can spread during floods

A floodplain is a relatively flat area beside a river that may receive rich deposits of soil when the river overflows. These deposits can make the land productive for farming, but the same location can be exposed to future floods. When water levels rise, the river may spread across the plain, damaging homes, crops, roads and other property. Therefore, option C is correct. Fertility offers an advantage, but it does not remove the physical risk of flooding.

The reasoning requires considering both benefits and hazards. River flooding can leave nutrient-rich sediment, which explains why people may value floodplain land. However, a floodplain is formed or affected by the river’s overflow, so it remains a natural area of possible water spread. The choices saying water never reaches the area or that fertile land is always safe are clearly incorrect. Soil does not normally become rock simply because the land is a floodplain. Thus, option C gives the accurate reason for settlement risk.