Answer:
Siltation is a process by which water becomes dirty as a result of fine mineral particles in the water. Explanation: When sediment, or silt, is suspended in water, this is an example of siltation.
I think it is C. However, it should just be rock and water/ice.
C. Somalia
All of the other countries listed have pretty stable governments in place whereas in Somalia a lot of it is ungoverned or under anarchy.
The Rocky Mountains are described as younger because the Rocky's are really two mountain chains. The older mountain chain started billions of years ago, and the younger mountain chain pushed the older mountain chain up more, only 60 millions years ago.