Final answer:
In a slump, the correct answer is C) backwards rotation, which is a distinctive characteristic of this type of mass wasting event.
Step-by-step explanation:
A slump is a type of mass wasting event characterized by the movement of soil or rock on a portion of a slope. This movement typically results in a distinct headscar and is recognizable by the material's backwards rotation as it moves downslope. Therefore, the correct answer is C) backwards rotation.
Slumps often occur as part of a complex process involving various geologic activities. They can be triggered by factors such as erosion, excessive precipitation, earthquakes, and human activities that destabilize the slope. Importantly, slumps differ from other forms of mass wasting in that the displaced material rotates along a curved surface at the failure zone, which often leaves the material relatively intact but tilted backwards.