Given the task definition and input, reply with output. You are given a science question (easy-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each 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?
(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.
B