Discovering the Dangers

• The growth of the human population
• The contamination of air by harmful substances including gases and smoke (correct)
• The process of heating and cooling homes
• The production of electricity

• Heating and cooling homes
• Fueling vehicles
• Producing electricity
• All of the above (correct)

• It contributes to air pollution (correct)
• It leads to the growth of the human population
• It causes contamination of air by harmful substances
• It results in air pollution