OK so when I did this the answer was a and I got it right
Weakened rock on steep slopes that suddenly gives away and falls down is an example of : A. The impact of Gravity.
Gravity will always caused forces that pulled the rock down. Eventually, the rock on steep slopes will be weakened and pulled by the Gravity
hope this helps
It is all of the following:
250 Species of mammals, 600 species of birds, 200 Species of reptiles and amphibians, along with many species of butterflies and other insects.