Final answer:
Mountain ranges in the western United States often appear closer due to aerial perspective.
Step-by-step explanation:
The correct answer is d. aerial perspective. Mountain ranges in the western United States often appear to be much closer than they really are due to aerial perspective. Aerial perspective refers to the phenomenon where the distance between objects appears greater as the objects get farther away. In this case, the mountains in the western United States may appear closer because of atmospheric conditions and the way light interacts with particles in the air.
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