Correct Response: C. Turbidity currents form when gravity and seafloor currents move massive volumes of river sediment over the continental shelf. Turbidity currents can occur when large amounts of sediment accumulated near the edge of the continental shelf collapse due to their own weight or from the shaking of an earthquake. The sediments rapidly flow down the slope, carving out a submarine canyon in the process. Although earthquakes and settling can cause cracks in shelf sediments (A), this mechanism is not in itself sufficient to create submarine canyons. Movement along offshore faults (B) may trigger a turbidity current, but in itself faulting is not what forms submarine canyons. Freshwater is less dense than saline ocean water and therefore does not play a role in scouring out submarine canyons (D) that cut to the bottom of the continental rise.
