The correct options are
B Factories
C Traffic
D Coal-based power plants
Factories release a large amount of smoke into the air. This smoke contains pollutants like carbon monoxide, sulfur dioxide and nitrogen dioxide, which in turn contribute to the greenhouse effect.
Traffic is made by excessive automobiles, most of which use fossil fuels like petrol and diesel. The burning of these fuels also leads to the emission of greenhouse gases.
Coal-based power plants also release a lot of pollutants into the air. The main emissions from coal-based power plants that contribute to air pollution include sulphates, nitrates, mercury, and secondary particulate matter.