A bulldozer pushes a pile of dirt. A shoe makes a footprint in soil. A tree root splits a rock in half. A drill makes a hole in a board.
Which is most similar to the way a glacier makes a valley?

Options:
- A bulldozer pushes a pile of dirt.
- A shoe makes a footprint in soil.
- A tree root splits a rock in half.
- A drill makes a hole in a board.

A bulldozer pushes a pile of dirt.