The correct answer is - B. biodiversity.
The damming is effecting very negatively the biodiversity in the river systems. It stops the natural movement of the species, rising the temperature of the water, as well as the movement of the nutrients through the water. This disables the species to feed themselves properly, or mate, and changes their environment, so very often, lots of species die out.
Deforestation is perfect example of reducing the biodiversity. The forests provide shelter, habitat, food source, for both the animals and plants, and once they are gone, the other flora and fauna is left out on the open without anything, and it dies out.
