Question

1. a river carries sediment downstream over time. what is the main process responsible for this movement?

weathering by acid rain
deposition by gravity
melting by sunlight
erosion by running water

Explanation:

Running water in a river has the force to pick up and carry sediment downstream, which is the process of erosion. Weathering by acid - rain breaks down rocks but doesn't directly carry sediment downstream. Deposition is the process of sediment being dropped, not carried. Melting by sunlight is not relevant to sediment movement in a river.

Answer:

Erosion by running water