Question

in 1935, the hoover dam, one of the most famous hydroelectric projects in history, was completed on the border of nevada and arizona. the dam, built on the colorado river, was created for three purposes: providing irrigation water, controlling floods, and ——? which additional purpose best completes this excerpt? providing cool air through air conditioning creating farmland in a stair step pattern monitoring tectonic movement during earthquakes generating electricity

Explanation:

Hydroelectric projects like the Hoover Dam generate electricity. The other options (monitoring tectonic movement, creating farmland in a stair - step pattern, providing cool air through air conditioning) are not typical purposes of a hydroelectric dam. Hydroelectric dams use the flow of water to turn turbines and produce electrical energy.

Answer:

generating electricity