Question

in what time period did hydroelectric power usage reach its peak?
1970–1980
1980–1990
1990–2000
2000–2010

Explanation:

Step1: Analyze the hydroelectric power line

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

Step2: Identify the peak

Check the highest point of the blue line within the given time - period options.

Answer:

2000 - 2010