Which is most likely cause of springtime flooding in a river valley? a. rapid snow melt in regions upstream b. erosion of the natural stream channel c. moderate rainfall in the region d. an increase in sediment load

A.  Rapid snow melt in regions upstream

Explanation:

"Rapid snow melt" in the upstream regions is most likely the cause of spring time flooding in a river valley. The effects of rapid snow melt are different for different areas. But in the upstream region it is a concern. In the spring time the rapid snow melting has become a cause of concern for many people around the world. But besides flooding snow melting can cause "landslides and debris flows" too. In the "alpine regions" like "Switzerland", snowmelt is a major cause for the runoff. Snow melting in such regions with the combination of rain can cause disastrous floods.

d.) greenhouse gases