Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: A student climbs up a rocky mountain trail in Maine. She sees many small pieces of rock on the path. Which action most likely made the small pieces of rock?
ice breaking large rocks apart
Weathering.