Which of these is a natural source of pollution?

A) rain

B) pesticides

C) dust storms

D) fossil fuels

The correct answer is "dust storms".

First of all, rain, unless it is acid rain, is not a source of pollution although it is a natural phenomena. Pesticides and fossil fuels both cause pollution but they are a man-made phenomena not natural. Dust storms produce pollution in the air by swifting dust rendering the air almost unhabitable. This is a natural occurence and at the same time, pollutes.