Answer:
B
Explanation:
It removes other waste from our body and keeps our blood clean
Plant cells have what is perhaps the most complex outer coverings. Plant cell walls are made largely of cellulose which forms strong, highly rigid, almost indigestible coverings that protect the cell and gives it shape.
If the gradient or slope is high then the water flow will go faster because suppose water is flowing down from a skateboard ramp, it would flow faster than water flowing throw a straight pipe.
Here's a picture I drew to help you!