What Factor in This Image Would Control the Depth of This

Multiple Choice

What factor in this image would control the depth of this feature? (What might stop it from getting deeper?)

A) Presence of large boulders will stop the wind.
B) Sediment will be frozen in place.
C) Scouring will go down to bedrock and run out of sediment.
D) Presence of vegetation will hold sediment in place.