Which type of sediment remains suspended in water and is often made of lighter materials?

The correct choice is the type of sediment known as silt and clay suspended load, which consists of finer particles that can remain suspended in water for extended periods. This is primarily due to their small size and lower density compared to larger sediments, which allows them to be easily carried by the flow of water.

In a water body, factors such as turbulence and flow velocity help maintain these fine sediments in suspension rather than allowing them to settle to the bottom. Silt and clay particles, being smaller than sand or gravel, experience greater interactions with water molecules, which further supports their suspension in the water column.

The understanding of suspended load is crucial when analyzing sediment transport in rivers and streams, as it plays a significant role in water quality and aquatic ecosystems.