How does the use of hydroelectric energy compare to the use of coal? a.
Hydroelectric energy is more commonly used than coal.
b.
Hydroelectric energy is associated with less waste production than coal.
c.
Hydroelectric energy has a larger environmental impact than coal use.
d.
Hydroelectric energy requires more land space than coal use.

Which of the following is likely not involved in this example of ecological succession? a) the rotting remains of plants add to the fertility of the soil. b)the soil becomes so fertile that eel grass is replaced by other plant species. c) the roots from plants stabilize the sediment, keeping it in place. d) the concentration of salt becomes so high that all plant life is destroyed.