Arockfall is best described as: select one:

a. a landslide induced by the liquefaction of sediment during an earthquake
b. the gradual movement of soil downslope over the course of years or even centuries
c. the rotational movement of soil downslope that occurs along a curved surface of rupture
d. the rotational movement of soil downslope that occurs along a planar surface of rupture
e. a non-cohesive soil flow made up of sand to boulder sized sediments that is triggered by intense rainfall or rapid snow melt
f. a mass of rock dislodged from a steep slope that free falls, bounces or rolls downslope
g. a cohesive soil flow made up of mostly fine grained sediments (e. g., silt, clay and sand) that is triggered by intense rainfall or rapid snow melt