Answer:
b) Soil material being moved downstream carried by water
Step-by-step explanation:
Erosion can be defined as a geological process which typically involves the wearing out of earthen (soil) materials and the transportation of these materials by natural forces like water, wind, etc. Soil erosion is greatest when the soil is steep.
The steepness of a body such as river or stream refers to the downward slope or gradient of the body of water.
Generally, the steepness of a body affects the rate at which other materials would flow or move around. Thus, the steeper a river or stream, the greater would be its rate of erosion.
An example of erosion in action is soil material being moved downstream carried by water.