The effects of deforestation include:
- Air pollution
- Soil erosion
- Water pollution
Among the options provided, all except "earthquakes" are effects of deforestation. Deforestation does not directly cause earthquakes. Therefore, any of the first three responses (air pollution, soil erosion, or water pollution) could be considered correct. If you have to choose just one, "soil erosion" is a particularly significant and direct effect of deforestation.