Answer:
D
Step-by-step explanation:
A is wrong because sediment is what has been eroded, not what gets eroded. B is wrong because more physical weathering would occur in faster waters. C is wrong because water, for the most part, has no chemical reaction with it's surroundings when it's found in a river. Also, with the slow and shallowness, the sediment had more time to settle at the bottom and is more likely to do so