4th option. the movement of people to cities.
A once smooth road surface has cracks and fractures, plus a large pothole. While plate tectonics forces work to build huge mountains and other landscapes, the forces of weathering gradually wear those rocks and landscapes away. Together with erosion, tall mountains turn into hills and even plains.
Answer:
A secondary source is a source from a second hand perspective that DID NOT experience the event first handed but is writing about the event without the origional experience of the event. An example of this would be the topic of World War 1, a secondary source would be a news article or a book talking about the war without actually experiencing it. But a primary source would be a autobiography of a person experiencing World War 1. Another great example is that a secondary soource is a biography of someone while a primary source is a autobiography of a person.
Explanation:
