In the Figure Below,what About These Two Mass-Wasting Events Is

In the figure below,what about these two mass-wasting events is similar and what is different?

A) Both involve water,but mass-wasting event b could not have occurred in the mountains.
B) Both occur in the mountains,but mass-wasting event a moved much faster.
C) Both involve water,but the water is in two different phases.
D) Both occur in the mountains but at two very different elevations.