What factors that influence mass movement of particles

Mass movement, which is sometimes called waste movement or slope movement, is defined as the large movement of rock, soil and debris downward due to the force of gravity.

1.  Slope  

    - Gravity provides the energy to move the materials.  

    - Rapid movements (e.g. landslide, slumping) etc.

2.  Water

     - Rainwater acts as a lubricant to weathered materials.  

     - Rainwater adds weight to weathered materials.  

3.   Rock structure  

     - Joints dipping downslope usually assists landslides, rockfalls, rockslide etc

4.  Vegetation  

     - Lack of vegetation cover to hold the loose particles.  

5.  Vibrations  

     - Earthquakes.  

     - Construction processes and mining operations.

i think it's c

this is more of a statement than a question. is there answers to go along with this, or is it opinion based?