Given the question: Answer the following question given this paragraph: This picture shows a thick layer of smog and dust over a very polluted city (Singapore). Smog in the air is a serious health hazard for people living in many big cities around the globe. Smog is one example of air pollution. Q: Smog is one example of what type of pollution? Choices: - light - energy - sound - air A:
The answer is:
air