Which of the following makes the use of hydropower to generate electricity controversial?
Hydropower was first used to turn water wheels to grind grain.
Some countries use hydropower as their main source of electricity.
Dams can be built to store water. Releasing the stored water as needed allows a power plant to operate in all weather conditions.
Generating hydropower requires the damming of rivers. Dams can disturb the migration and spawning of fish populations in the river.