Final answer:
The movement of material downslope along a curved surface is known as a slump, which is a type of landslide often triggered by water saturation along with other contributing factors such as erosion, saturation, and seismic activities. The correct answer is option c.
Step-by-step explanation:
When a mass of material moves downslope along a curved surface, the process is called slump. A slump typically occurs when the slope material, often saturated with water, moves down a concave-upward or curved surface. Contribution factors for such movements include erosion by rivers, glaciers, or ocean waves that create over-steepened slopes, saturation by snowmelt or heavy rains that weaken the rock and soil slopes, and stresses resulting from earthquakes or the excess weight from various sources.
Landslides are a broader term encompassing various types of ground movements such as rock falls, deep slope failures, and shallow debris flows. Besides gravity acting on an over-steepened slope, other phenomena like subsidence, glacial isostatic adjustments, erosion, or volcanic eruptions can also contribute to landslides, with each type having distinct characteristics and implications.