Question

study the graph.
renewable energy consumption by source, 1949 - 2011
in what time period did hydroelectric power usage reach its peak?
1970 - 1980
mark this and return save and exit next

Explanation:

Step1: Analyze the hydroelectric power curve

Look at the blue line (hydroelectric power) in the graph.

Step2: Identify the highest point

Find the highest point on the hydroelectric power curve.

Step3: Determine the time period

Check the x - axis (time) corresponding to the highest point. The highest point of the hydroelectric power curve is in the 1970 - 1980 time period.

Answer:

1970–1980