Earth's atmosphere is able to gradually refract light rays:
A) only when it is very dry.
B) only when the sun is very high in the sky.
C) because of the changing density of air as you get closer to the surface.
D) because of air pollution that is present.
Question 2
Which of the following is not cited as a factor in helping to reduce air pollution?
A) use of more alternative, clean energy sources such as wind and solar
B) increased vehicle fuel-efficiency
C) uses of alternative and public transportation
D) stricter air emission regulations
E) increased use of coal as an energy source
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