A
Below is a question with multiple-choice answers. Choose the correct option based on your reasoning.

### Question:
Some plant species are more tolerant of acidic soil than others. The tolerant species are favored in areas affected by which consequence of human activity?

### Choices:
A. mixing of pollutants with rain
B. erosion of topsoil by clearcutting
C. runoff of fertilizer used in farming
D. thinning of the atmospheric ozone layer

### Answer:
