The correct answer would be D. footnote
The Niles water would be collected during the summer season because that's when the water would rise. This helped the Egyptians to grow their crops however the Nil would often flood and cause destruction to the surrounding land and crops.
The answer is weathering. Weathering is where rocks or other materials are broken down because of forces like wind or water. This is different than erosion, which is the process where the broken down materials are moved.
