Question

The chemical and physical actions of groundwater form

Karst topography

glacial topography

volcanic topography

mountain topography

Answer 1

Karst would be my guess by process of elimination.

Answer 2

By the questions own wording we are dealing with ground water and not glaciers, volcanoes or mountains.
Well maybe mountains, but I doubt it.

Answer 3

@jaga, you should have defined Karst.

Answer 4

Can't. I'm a computer scientist not a geologist. Don't have a clue what Karst is.

Answer 5

I was just looking at it logically.

Answer 6

So you both say Karst