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.

A. Preventing fish from moving along a river.

Explanation:

1. Dams create barriers and trap the water that builds up behind it. This prevents fish from moving along the river as there's a barrier in place and is just overall harder for the fish to move freely along a river because of it.

2. It's the only negative option as the others are all positive outcomes, while the question asks for a negative outcome instead.

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phylogenetic tree is the tree of life or evolution tree. it shows the different branches of evolution. the sequence goes like tissues - coelom - backbone - endoskeleton - segmentation

this would be a math