a mountain eroding to a hill a river making a delta a glacier making a canyon a storm moving a sandbar
I gave my students this multiple choice question: Changes to Earth's surface can happen slowly or quickly. Which of these changes happens the most quickly?

Only one answer is correct among these 4 choices:
- a mountain eroding to a hill
- a river making a delta
- a glacier making a canyon
- a storm moving a sandbar

Could you tell me which one is correct?

a storm moving a sandbar