Q:Fact 1: Most canyons are formed by flowing rivers through erosion over long periods of time. Fact 2: Rivers contain 0.001 percent of the earth's water. Given the two facts above, answer the question "What are most canyons caused by?" with the following options: - erosion - Physical weathering - magic - Freezing temperature - Flowing water - ice wedging - Flowing gas - flooding
A:
Flowing water