a raindrop splashing in a lake a snowball rolling down a mountain a river washing away soil from its bank a tree root growing into the crack of a rock
I gave my students this multiple choice question: Weathering causes rocks and minerals to break into smaller pieces. Which event is the best example of weathering?

Only one answer is correct among these 4 choices:
- a raindrop splashing in a lake
- a snowball rolling down a mountain
- a river washing away soil from its bank
- a tree root growing into the crack of a rock

Could you tell me which one is correct?

a tree root growing into the crack of a rock