Question

Where a river flows from an area of harder rock to an area of softer rock, the softer rock may wear away, eventually forming a drop called a(n)
a.
oxbow lake.
b.
gully.
c.
waterfall.
d.
delta.

Answer 1

Where a river flows from an area of harder rock to an area of softer rock, the softer rock may wear away, eventually forming a drop called a waterfall.

A waterfall is a body of water in which water flows over the edge of a cliff into a plunge pool under it. Waterfall usually forms as rivers flow over various bands of rocks; from hard rock to soft rock both vertically and laterally. The soft rock is being eroded away, undercutting the hard rock which later collapse. A hard ledge is formed over which the stream falls. This way, a waterfall is formed.

Answer 2

Where a river flows from an area of harder rock to an area of softer rock, the softer rock may wear away, eventually forming a drop called a "Waterfall"

In short, Your Answer would be Option C

Hope this helps!