a mountain eroding to a hill a river making a delta a glacier making a canyon a storm moving a sandbar
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Changes to Earth's surface can happen slowly or quickly. Which of these changes happens the most quickly?
Possibilities:
- a mountain eroding to a hill
- a river making a delta
- a glacier making a canyon
- a storm moving a sandbar

a storm moving a sandbar