Final answer:
The statement is b. False. Soil creep is a very slow movement, usually measured in millimeters to centimeters per year, not kilometers. Larger and faster soil movements are associated with landslides or mudflows, which are driven by external stresses such as heavy rainfall or earthquakes.
Step-by-step explanation:
The statement that soil creep can carry materials as much as a kilometer downhill in a single year is False. Soil creep is a very slow process that causes downslope movement of soil and rock. It typically occurs over a long period and the speed at which soil creep happens is usually on the order of millimeters to centimeters per year, not kilometers.
Landslides are a different and much faster phenomenon where soil and rock may move a considerable distance in a short period, especially when saturated by heavy rainfall or destabilized by events like earthquakes. On the other hand, erosion by rivers, glaciers, or ocean waves can create over-steepened slopes that may lead to larger mass movements such as landslides or mudflows.
Furthermore, while soil development over time can lead to a more stable landscape, the addition of external stresses like earthquakes or excessive weight from rainfall can destabilize slopes and lead to sudden, significant soil movements. But these are not to be confused with the gradual process of soil creep.