问题详情

In what way can natural pollutants play an important role in controlling air pollution？
A.They function as part of a purification process.
B.They are dwarfed by the pollutants produced by human activities.
C.They are less harmful to living beings than are other pollutants.
D.They have existed since the Earth developed.请帮忙给出正确答案和分析，谢谢！