Question: 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?

  Options: 
 A. It will put acid into the lakes and ponds.
 B. It will begin the process of building soil.
 C. It will prevent the carbon cycle from occurring.
 D. It will prevent bacteria from invading the ecosystem.
Answer: B