Here's a problem to solve: A student prepared a presentation to show how water changes the surface of Earth. Which presentation would best demonstrate how water changes the surface of Earth?

Among the 4 following options, which is the correct answer?

- A: a diagram of a river food web
 
- B: a graph of the amount of rainfall on a lake
 
- C: a picture of fog covering a mountain valley
 
- D: a model of a stream flowing down a hillside
 