From 20 13 to1June, a large area of smog weather occurred in the central and eastern regions of China, and the air was seriously polluted. The following phenomena are closely related to the formation of haze weather.

Because minerals are used as fuel in industrial production, a large number of pollutants are discharged into the air, coupled with a large number of automobile exhaust emissions, heating in winter also discharges dust into the air, resulting in a large number of tiny dust particles, smoke particles or salt particles suspended in the atmosphere, forming smog.

So choose: a.