What are the main factors that can cause instability in sterile waste piles? Elevation of the water table in the pile mass Saturation of the slope ...

What are the main factors that can cause instability in sterile waste piles?
Elevation of the water table in the pile mass
Saturation of the slope and surface flow parallel to its face
The inadequate drainage of surface and subsurface water is a common cause of geotechnical instability in sterile waste piles.
The physical characteristics of the sterile waste material are the only factors that influence the occurrence of instability in sterile waste piles.
The improper disposal and revegetation of sterile waste material can create an environment favorable to the occurrence of environmental liabilities.
a) Only I is correct.
b) I and III are correct.
c) I and II are correct.
d) I, II, and III are correct.