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 glacier retreats leaving bare rocks. Lichens begin to live on the rocks. The lichens produce an acid that starts to break down the rocks. How will this process affect the environment?
It will begin the process of building soil.
The rocks will weather more rapidly.