Dams are barriers that prevent the flow of water. They are created to provide flood control, recreational areas, water for irrigation, and hydroelectric power. Although dams serve many important purposes, they can also have a negative impact on the environment by
A.
preventing fish from moving along a river.
B.
serving as a place for people to have picnics.
C.
increasing fresh water sources for humans.
D.
providing new wildlife habitats.