The correct answer is (b) Water is filtered as it passes through the root system of the trees.
Trees play an important role in maintaining a healthy water by improving its quality. The roots absorb carbon dioxide and releases oxygen into the water making it usable for. Roots absorb nutrients and results in clearer water and less algae. A variety of trees can be used for this purpose. As the water moves through the roots of the trees the extra pollutants that makes the water dirty are removed by them.
