What would be the parent material of soil that is moved by a river and then redeposited?

The parent material of soil that is moved by a river and subsequently redeposited is alluvium. Alluvium is characterized by sediment that has been transported and deposited by flowing water, typically in riverbeds, floodplains, or deltas. This material is usually composed of a variety of particle sizes, including sand, silt, and clay, and is often nutrient-rich, making it advantageous for agriculture and plant growth.

In contrast, bedrock refers to the solid rock underlying the soil, which does not change due to water movement. Glacial till is sediment that has been deposited directly by glacial action, comprising a mix of various particle sizes without the sorting that occurs in alluvial deposits. Colluvium, on the other hand, consists of materials that have been moved by gravity, such as debris that has fallen down slopes, rather than by the action of water. This distinction highlights why alluvium is the correct answer in the context of soil formation related to river activity.